diff --git a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/business/RollUseCase.kt b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/business/RollUseCase.kt
index c5319e0..daaf063 100644
--- a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/business/RollUseCase.kt
+++ b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/business/RollUseCase.kt
@@ -1,19 +1,7 @@
 package com.pixelized.desktop.lwa.business
 
-import com.pixelized.desktop.lwa.repository.characterSheet.model.CharacterSheet
-
 object RollUseCase {
 
-    private val diceParser = Regex(
-        """(?<sign>[+-])?\s*(?<modifier>[ade])?(?<quantity>\d+)[dD](?<face>\d+)"""
-    )
-    private val flatParser = Regex(
-        """(?<sign>[+-])?\s*[^a-zA-Z](?<value>\d+)\b"""
-    )
-    private val paramParser = Regex(
-        """(?<sign>[+-])?\s*(?<param>BDGT)\b"""
-    )
-
     fun rollD100(): Int {
         return roll(quantity = 1, faces = 100)
     }
@@ -22,39 +10,6 @@ object RollUseCase {
         return sum(count = quantity) { (Math.random() * faces.toDouble() + 1).toInt() }
     }
 
-    fun roll(characterSheet: CharacterSheet, roll: String): Int {
-        println(roll)
-        return diceParser.findAll(roll).sumOf { match ->
-            val (sign, modifier, quantity, faces) = match.destructured
-            ((if (sign == "-") -1 else 1) * roll(
-                quantity = quantity.toInt(),
-                faces = faces.toInt()
-            )).also {
-                println("roll ${sign}${quantity}d${faces} -> $it")
-            }
-        } + flatParser.findAll(roll).sumOf { match ->
-            val (sign, value) = match.destructured
-            ((if (sign == "-") -1 else 1) * value.toInt()).also {
-                println("flat: ${sign}${value} -> $it")
-            }
-        } + paramParser.findAll(roll).sumOf { match ->
-            val (sign, param) = match.destructured
-            (if (sign == "-") -1 else 1) * when (param) {
-                "BDGT" -> diceParser.findAll(characterSheet.damageBonus).sumOf {
-                    val (sign, modifier, quantity, faces) = it.destructured
-                    ((if (sign == "-") -1 else 1) * roll(
-                        quantity = quantity.toInt(),
-                        faces = faces.toInt()
-                    )).also {
-                        println("param: ${sign}${param} -> $it")
-                    }
-                }
-
-                else -> 0
-            }
-        }
-    }
-
     private fun sum(count: Int, block: () -> Int): Int {
         return if (count > 1) {
             block() + sum(count - 1, block)
diff --git a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/business/SkillValueComputationUseCase.kt b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/business/SkillValueComputationUseCase.kt
index fc762a2..366ed01 100644
--- a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/business/SkillValueComputationUseCase.kt
+++ b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/business/SkillValueComputationUseCase.kt
@@ -1,39 +1,110 @@
 package com.pixelized.desktop.lwa.business
 
+import com.pixelized.desktop.lwa.parser.arithmetic.ArithmeticParser
 import com.pixelized.desktop.lwa.parser.arithmetic.Instruction
 import com.pixelized.desktop.lwa.repository.characterSheet.model.CharacterSheet
 import kotlin.math.max
 
-class SkillValueComputationUseCase {
-
+class SkillValueComputationUseCase(
+    private val arithmeticParser: ArithmeticParser,
+) {
     fun computeSkillValue(
         sheet: CharacterSheet,
         skill: CharacterSheet.Skill,
         diminished: Int,
     ): Int {
-        val baseSum = skill.base.sumOf {
-            when (val instruction = it.instruction) {
+        val baseSum = arithmeticParser.parse(skill.base).sumOf { instruction ->
+            when (instruction) {
                 is Instruction.Dice -> 0
-                is Instruction.Flat -> instruction.value
-                Instruction.Word.BDC -> 0
-                Instruction.Word.BDD -> 0
-                Instruction.Word.STR -> sheet.strength
-                Instruction.Word.DEX -> sheet.dexterity
-                Instruction.Word.CON -> sheet.constitution
-                Instruction.Word.HEI -> sheet.height
-                Instruction.Word.INT -> sheet.intelligence
-                Instruction.Word.POW -> sheet.power
-                Instruction.Word.CHA -> sheet.charisma
-            } * it.sign
+
+                is Instruction.Flat -> {
+                    instruction.value
+                }
+
+                is Instruction.Word -> {
+                    when (instruction.type) {
+                        Instruction.Word.Type.BDC -> 0
+                        Instruction.Word.Type.BDD -> 0
+                        Instruction.Word.Type.STR -> sheet.strength
+                        Instruction.Word.Type.DEX -> sheet.dexterity
+                        Instruction.Word.Type.CON -> sheet.constitution
+                        Instruction.Word.Type.HEI -> sheet.height
+                        Instruction.Word.Type.INT -> sheet.intelligence
+                        Instruction.Word.Type.POW -> sheet.power
+                        Instruction.Word.Type.CHA -> sheet.charisma
+                    }
+                }
+            } * instruction.sign
         }
+
         val base = if (skill.occupation) {
             max(MIN_OCCUPATION_VALUE, baseSum)
         } else {
             baseSum
         }
+
         return max(base + skill.bonus + skill.level - diminished, 0)
     }
 
+    fun computeRoll(
+        sheet: CharacterSheet,
+        roll: String,
+    ): Int { // TODO Roll detail instead of an simple Int.
+        print("Roll ->")
+        return arithmeticParser.parse(roll).sumOf { instruction ->
+            val value = when (instruction) {
+                is Instruction.Dice -> RollUseCase.roll(
+                    quantity = instruction.quantity,
+                    faces = instruction.faces
+                )
+
+                is Instruction.Flat -> instruction.value
+
+                is Instruction.Word -> {
+                    when (instruction.type) {
+                        Instruction.Word.Type.BDC -> {
+                            val damageBonusInstructions = arithmeticParser
+                                .parse(sheet.damageBonus)
+                                .firstOrNull()
+                            if (damageBonusInstructions is Instruction.Dice) {
+                                RollUseCase.roll(
+                                    quantity = damageBonusInstructions.quantity,
+                                    faces = damageBonusInstructions.faces
+                                )
+                            } else {
+                                0
+                            }
+                        }
+
+                        Instruction.Word.Type.BDD -> {
+                            val damageBonusInstructions = arithmeticParser
+                                .parse(sheet.damageBonus)
+                                .firstOrNull()
+                            if (damageBonusInstructions is Instruction.Dice) {
+                                RollUseCase.roll(
+                                    quantity = damageBonusInstructions.quantity,
+                                    faces = damageBonusInstructions.faces
+                                ) / 2
+                            } else {
+                                0
+                            }
+                        }
+
+                        Instruction.Word.Type.STR -> sheet.strength
+                        Instruction.Word.Type.DEX -> sheet.dexterity
+                        Instruction.Word.Type.CON -> sheet.constitution
+                        Instruction.Word.Type.HEI -> sheet.height
+                        Instruction.Word.Type.INT -> sheet.intelligence
+                        Instruction.Word.Type.POW -> sheet.power
+                        Instruction.Word.Type.CHA -> sheet.charisma
+                    }
+                }
+            } * instruction.sign
+
+            value.also { print(" ($instruction):$it") }
+        }.also { println() }
+    }
+
     companion object {
         private const val MIN_OCCUPATION_VALUE = 40
     }
diff --git a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/parser/arithmetic/ArithmeticParser.kt b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/parser/arithmetic/ArithmeticParser.kt
index 1bac89c..af8e397 100644
--- a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/parser/arithmetic/ArithmeticParser.kt
+++ b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/parser/arithmetic/ArithmeticParser.kt
@@ -21,13 +21,13 @@ class ArithmeticParser {
     )
 
     @Throws(Instruction.UnknownInstruction::class)
-    fun parse(value: String): List<Arithmetic> {
+    fun parse(value: String): List<Instruction> {
         return operatorParser.findAll(value).mapNotNull {
             val (operator, instruction) = it.destructured
             if (instruction.isNotBlank()) {
-                Arithmetic(
+                parseInstruction(
                     sign = parseOperator(operator),
-                    instruction = parseInstruction(instruction),
+                    instruction = instruction,
                 )
             } else {
                 null
@@ -36,10 +36,14 @@ class ArithmeticParser {
     }
 
     @Throws(Instruction.UnknownInstruction::class)
-    fun parseInstruction(instruction: String): Instruction {
+    fun parseInstruction(
+        sign: Int,
+        instruction: String
+    ): Instruction {
         diceParser.find(instruction)?.let {
             val (modifier, quantity, faces) = it.destructured
             Instruction.Dice(
+                sign = sign,
                 modifier = parseModifier(value = modifier),
                 quantity = quantity.toInt(),
                 faces = faces.toInt(),
@@ -47,11 +51,17 @@ class ArithmeticParser {
         }?.let { return it }
 
         wordParser.find(instruction)?.let {
-            parseWord(value = it.value)
+            parseWord(
+                sign = sign,
+                value = it.value
+            )
         }?.let { return it }
 
         flatParser.find(instruction)?.let {
-            Instruction.Flat(value = it.value.toInt())
+            Instruction.Flat(
+                sign = sign,
+                value = it.value.toInt(),
+            )
         }?.let { return it }
 
         throw Instruction.UnknownInstruction(payload = instruction)
@@ -74,31 +84,39 @@ class ArithmeticParser {
         }
     }
 
-    private fun parseWord(value: String): Word? {
+    private fun parseWord(
+        sign: Int,
+        value: String,
+    ): Word? {
         return try {
-            Word.valueOf(value)
+            Word(
+                sign = sign,
+                type = Word.Type.valueOf(value),
+            )
         } catch (_: Exception) {
             return null
         }
     }
 
     fun convertInstructionToString(
-        instructions: List<Arithmetic>,
+        instructions: List<Instruction>,
     ): String {
         return instructions.map {
             val sign = if (it.sign > 0) "+" else "-"
-            val value = when (val instruction = it.instruction) {
-                is Instruction.Dice -> "${instruction.modifier ?: ""}${instruction.quantity}d${instruction.faces}"
-                is Instruction.Flat -> "${instruction.value}"
-                Word.BDC -> Word.BDC.name
-                Word.BDD -> Word.BDD.name
-                Word.STR -> Word.STR.name
-                Word.DEX -> Word.DEX.name
-                Word.CON -> Word.CON.name
-                Word.HEI -> Word.HEI.name
-                Word.INT -> Word.INT.name
-                Word.POW -> Word.POW.name
-                Word.CHA -> Word.CHA.name
+            val value = when (it) {
+                is Instruction.Dice -> "${it.modifier ?: ""}${it.quantity}d${it.faces}"
+                is Instruction.Flat -> "${it.value}"
+                is Word -> when (it.type) {
+                    Word.Type.BDC -> Word.Type.BDC.name
+                    Word.Type.BDD -> Word.Type.BDD.name
+                    Word.Type.STR -> Word.Type.STR.name
+                    Word.Type.DEX -> Word.Type.DEX.name
+                    Word.Type.CON -> Word.Type.CON.name
+                    Word.Type.HEI -> Word.Type.HEI.name
+                    Word.Type.INT -> Word.Type.INT.name
+                    Word.Type.POW -> Word.Type.POW.name
+                    Word.Type.CHA -> Word.Type.CHA.name
+                }
             }
             "$sign$value"
         }.joinToString(separator = " ") {
@@ -107,6 +125,6 @@ class ArithmeticParser {
     }
 
     companion object {
-        val words: List<String> = Word.entries.map { it.name }
+        val words: List<String> = Word.Type.entries.map { it.name }
     }
 }
\ No newline at end of file
diff --git a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/parser/arithmetic/Instruction.kt b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/parser/arithmetic/Instruction.kt
index 8d254d4..c945f88 100644
--- a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/parser/arithmetic/Instruction.kt
+++ b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/parser/arithmetic/Instruction.kt
@@ -1,40 +1,64 @@
 package com.pixelized.desktop.lwa.parser.arithmetic
 
-class Arithmetic(
+sealed class Instruction(
     val sign: Int,
-    val instruction: Instruction,
-)
-
-sealed interface Instruction {
-    data class Dice(
+) {
+    class Dice(
+        sign: Int,
         val modifier: Modifier?,
         val quantity: Int,
         val faces: Int,
-    ) : Instruction {
+    ) : Instruction(
+        sign = sign,
+    ) {
         enum class Modifier {
             ADVANTAGE,
             DISADVANTAGE,
             EMPHASIS,
         }
+
+        override fun toString(): String {
+            return "${sign.sign}${quantity}d${faces}"
+        }
     }
 
-    data class Flat(
+    class Flat(
+        sign: Int,
         val value: Int,
-    ) : Instruction
+    ) : Instruction(
+        sign = sign,
+    ) {
+        override fun toString(): String {
+            return "${sign.sign}${value}"
+        }
+    }
 
-    enum class Word : Instruction {
-        BDC, // Damages bonus for melee
-        BDD, // Damages bonus for range
-        STR, // Strength
-        DEX, // Dexterity
-        CON, // Constitution
-        HEI, // Height
-        INT, // Intelligence
-        POW, // Power
-        CHA, // Charisma
+    class Word(
+        sign: Int,
+        val type: Type,
+    ) : Instruction(
+        sign = sign
+    ) {
+        enum class Type {
+            BDC, // Damages bonus for melee
+            BDD, // Damages bonus for range
+            STR, // Strength
+            DEX, // Dexterity
+            CON, // Constitution
+            HEI, // Height
+            INT, // Intelligence
+            POW, // Power
+            CHA, // Charisma
+        }
+
+        override fun toString(): String {
+            return "${sign.sign}${type}"
+        }
     }
 
     class UnknownInstruction(payload: String) : RuntimeException(
         "Unknown instruction exception. Unable to parse the following payload:\"$payload\" into an instruction"
     )
+
+    val Int.sign: String get() = if (this > 0) "+" else "-"
 }
\ No newline at end of file
diff --git a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/repository/characterSheet/CharacterSheetJsonFactory.kt b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/repository/characterSheet/CharacterSheetJsonFactory.kt
index 870156b..96b280e 100644
--- a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/repository/characterSheet/CharacterSheetJsonFactory.kt
+++ b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/repository/characterSheet/CharacterSheetJsonFactory.kt
@@ -36,7 +36,7 @@ class CharacterSheetJsonFactory(
                 CharacterSheetJsonV1.Skill(
                     id = it.id,
                     label = it.label,
-                    base = arithmeticParser.convertInstructionToString(it.base),
+                    base = it.base,
                     bonus = it.bonus,
                     level = it.level,
                     occupation = it.occupation,
@@ -47,7 +47,7 @@ class CharacterSheetJsonFactory(
                 CharacterSheetJsonV1.Skill(
                     id = it.id,
                     label = it.label,
-                    base = arithmeticParser.convertInstructionToString(it.base),
+                    base = it.base,
                     bonus = it.bonus,
                     level = it.level,
                     occupation = it.occupation,
@@ -58,7 +58,7 @@ class CharacterSheetJsonFactory(
                 CharacterSheetJsonV1.Skill(
                     id = it.id,
                     label = it.label,
-                    base = arithmeticParser.convertInstructionToString(it.base),
+                    base = it.base,
                     bonus = it.bonus,
                     level = it.level,
                     occupation = it.occupation,
@@ -69,7 +69,7 @@ class CharacterSheetJsonFactory(
                 CharacterSheetJsonV1.Roll(
                     id = it.id,
                     label = it.label,
-                    roll = arithmeticParser.convertInstructionToString(it.roll),
+                    roll = it.roll,
                 )
             },
         )
@@ -117,7 +117,7 @@ class CharacterSheetJsonFactory(
                 CharacterSheet.Skill(
                     id = it.id,
                     label = it.label,
-                    base = arithmeticParser.parse(it.base),
+                    base = it.base,
                     bonus = it.bonus,
                     level = it.level,
                     occupation = it.occupation,
@@ -128,7 +128,7 @@ class CharacterSheetJsonFactory(
                 CharacterSheet.Skill(
                     id = it.id,
                     label = it.label,
-                    base = arithmeticParser.parse(it.base),
+                    base = it.base,
                     bonus = it.bonus,
                     level = it.level,
                     occupation = it.occupation,
@@ -139,7 +139,7 @@ class CharacterSheetJsonFactory(
                 CharacterSheet.Skill(
                     id = it.id,
                     label = it.label,
-                    base = arithmeticParser.parse(it.base),
+                    base = it.base,
                     bonus = it.bonus,
                     level = it.level,
                     occupation = it.occupation,
@@ -150,7 +150,7 @@ class CharacterSheetJsonFactory(
                 CharacterSheet.Roll(
                     id = it.id,
                     label = it.label,
-                    roll = arithmeticParser.parse(it.roll),
+                    roll = it.roll,
                 )
             },
         )
diff --git a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/repository/characterSheet/model/CharacterSheet.kt b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/repository/characterSheet/model/CharacterSheet.kt
index 47a2473..2ad8a68 100644
--- a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/repository/characterSheet/model/CharacterSheet.kt
+++ b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/repository/characterSheet/model/CharacterSheet.kt
@@ -1,7 +1,5 @@
 package com.pixelized.desktop.lwa.repository.characterSheet.model
 
-import com.pixelized.desktop.lwa.parser.arithmetic.Arithmetic
-
 data class CharacterSheet(
     val id: String,
     val name: String,
@@ -36,7 +34,7 @@ data class CharacterSheet(
     data class Skill(
         val id: String,
         val label: String,
-        val base: List<Arithmetic>,
+        val base: String,
         val bonus: Int,
         val level: Int,
         val occupation: Boolean,
@@ -46,7 +44,7 @@ data class CharacterSheet(
     data class Roll(
         val id: String,
         val label: String,
-        val roll: List<Arithmetic>,
+        val roll: String,
     )
 
     object CommonSkillId {
diff --git a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/screen/characterSheet/detail/CharacterSheetFactory.kt b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/screen/characterSheet/detail/CharacterSheetFactory.kt
index 31e7a24..7db79a6 100644
--- a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/screen/characterSheet/detail/CharacterSheetFactory.kt
+++ b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/screen/characterSheet/detail/CharacterSheetFactory.kt
@@ -2,6 +2,7 @@ package com.pixelized.desktop.lwa.screen.characterSheet.detail
 
 import com.pixelized.desktop.lwa.business.SkillValueComputationUseCase
 import com.pixelized.desktop.lwa.composable.tooltip.TooltipUio
+import com.pixelized.desktop.lwa.parser.arithmetic.ArithmeticParser
 import com.pixelized.desktop.lwa.repository.characterSheet.model.CharacterSheet
 import com.pixelized.desktop.lwa.repository.characterSheet.model.CharacterSheet.CommonSkillId
 import com.pixelized.desktop.lwa.screen.characterSheet.detail.CharacterSheetPageUio.Characteristic
@@ -51,6 +52,7 @@ import org.jetbrains.compose.resources.getString
 
 class CharacterSheetFactory(
     private val skillUseCase: SkillValueComputationUseCase,
+    private val arithmeticParser: ArithmeticParser,
 ) {
 
     companion object {
@@ -251,7 +253,7 @@ class CharacterSheetFactory(
                 if (it.roll.isNotEmpty()) {
                     CharacterSheetPageUio.Roll(
                         label = it.label,
-                        value = "TODO",//it.roll,
+                        value = it.roll,
                     )
                 } else {
                     null
diff --git a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/screen/characterSheet/edit/CharacterSheetEditFactory.kt b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/screen/characterSheet/edit/CharacterSheetEditFactory.kt
index e79673a..9529b19 100644
--- a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/screen/characterSheet/edit/CharacterSheetEditFactory.kt
+++ b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/screen/characterSheet/edit/CharacterSheetEditFactory.kt
@@ -4,9 +4,7 @@ import androidx.compose.runtime.State
 import androidx.compose.runtime.derivedStateOf
 import com.pixelized.desktop.lwa.business.DamageBonusUseCase
 import com.pixelized.desktop.lwa.business.SkillNormalizerUseCase.normalize
-import com.pixelized.desktop.lwa.parser.arithmetic.Arithmetic
 import com.pixelized.desktop.lwa.parser.arithmetic.ArithmeticParser
-import com.pixelized.desktop.lwa.parser.arithmetic.Instruction
 import com.pixelized.desktop.lwa.repository.characterSheet.model.CharacterSheet
 import com.pixelized.desktop.lwa.screen.characterSheet.common.SkillFieldFactory
 import com.pixelized.desktop.lwa.screen.characterSheet.common.occupation
@@ -94,12 +92,7 @@ class CharacterSheetEditFactory(
                 CharacterSheet.Skill(
                     id = editedSkill.id,
                     label = editedSkill.label,
-                    base = listOf(
-                        Arithmetic(
-                            sign = 1,
-                            instruction = Instruction.Flat(editedSkill.base.value)
-                        )
-                    ),
+                    base = "${editedSkill.base}",
                     bonus = editedSkill.bonus.value.value.toIntOrNull() ?: 0,
                     level = editedSkill.level.value.value.toIntOrNull() ?: 0,
                     occupation = editedSkill.option.checked.value,
@@ -113,7 +106,7 @@ class CharacterSheetEditFactory(
                 CharacterSheet.Skill(
                     id = editedSkill.id,
                     label = editedSkill.label.value.value,
-                    base = parser.parse(editedSkill.base.value.value),
+                    base = editedSkill.base.value.value,
                     bonus = editedSkill.bonus.value.value.toIntOrNull() ?: 0,
                     level = editedSkill.level.value.value.toIntOrNull() ?: 0,
                     occupation = editedSkill.options.occupation,
@@ -127,7 +120,7 @@ class CharacterSheetEditFactory(
                 CharacterSheet.Skill(
                     id = editedSkill.id,
                     label = editedSkill.label.value.value,
-                    base = parser.parse(editedSkill.base.value.value),
+                    base = editedSkill.base.value.value,
                     bonus = editedSkill.bonus.value.value.toIntOrNull() ?: 0,
                     level = editedSkill.level.value.value.toIntOrNull() ?: 0,
                     occupation = editedSkill.options.occupation,
@@ -138,7 +131,7 @@ class CharacterSheetEditFactory(
                 CharacterSheet.Roll(
                     id = "", // TODO
                     label = it.label.value,
-                    roll = parser.parse(value = it.unpack()),
+                    roll = it.unpack(),
                 )
             },
         )
@@ -345,7 +338,7 @@ class CharacterSheetEditFactory(
                     id = skill.id,
                     label = specialSkillsLabel,
                     labelValue = skill.label,
-                    baseValue = parser.convertInstructionToString(instructions = skill.base),
+                    baseValue = skill.base,
                     bonusValue = skill.bonus.takeIf { it > 0 }?.toString() ?: "",
                     levelValue = skill.level.takeIf { it > 0 }?.toString() ?: "",
                     options = run {
@@ -362,7 +355,7 @@ class CharacterSheetEditFactory(
                     id = skill.id,
                     label = magicSkillsLabel,
                     labelValue = skill.label,
-                    baseValue = parser.convertInstructionToString(instructions = skill.base),
+                    baseValue = skill.base,
                     bonusValue = skill.bonus.takeIf { it > 0 }?.toString() ?: "",
                     levelValue = skill.level.takeIf { it > 0 }?.toString() ?: "",
                     options = run {
diff --git a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/screen/roll/RollViewModel.kt b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/screen/roll/RollViewModel.kt
index 45d3314..6205cbd 100644
--- a/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/screen/roll/RollViewModel.kt
+++ b/composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/screen/roll/RollViewModel.kt
@@ -3,14 +3,13 @@ package com.pixelized.desktop.lwa.screen.roll
 import androidx.compose.animation.core.Animatable
 import androidx.compose.animation.core.Spring
 import androidx.compose.animation.core.spring
-import androidx.compose.animation.core.tween
 import androidx.compose.runtime.State
 import androidx.compose.runtime.mutableStateOf
 import androidx.lifecycle.ViewModel
-import com.pixelized.desktop.lwa.business.RollUseCase
 import com.pixelized.desktop.lwa.business.SkillStepUseCase
-import com.pixelized.desktop.lwa.repository.characterSheet.model.CharacterSheet
+import com.pixelized.desktop.lwa.business.SkillValueComputationUseCase
 import com.pixelized.desktop.lwa.repository.characterSheet.CharacterSheetRepository
+import com.pixelized.desktop.lwa.repository.characterSheet.model.CharacterSheet
 import com.pixelized.desktop.lwa.repository.roll.RollHistoryRepository
 import com.pixelized.desktop.lwa.screen.characterSheet.detail.CharacterSheetPageUio
 import com.pixelized.desktop.lwa.screen.roll.DifficultyUio.Difficulty
@@ -34,6 +33,7 @@ import org.jetbrains.compose.resources.getString
 class RollViewModel(
     private val characterSheetRepository: CharacterSheetRepository,
     private val rollHistoryRepository: RollHistoryRepository,
+    private val skillComputation: SkillValueComputationUseCase,
 ) : ViewModel() {
 
     private lateinit var sheet: CharacterSheet
@@ -168,11 +168,12 @@ class RollViewModel(
                             }
                         )
                     }
-                    val roll = if (rollAction == "1d100") {
-                        RollUseCase.rollD100()
-                    } else {
-                        RollUseCase.roll(characterSheet = sheet, roll = rollAction)
-                    }
+
+                    val roll = skillComputation.computeRoll(
+                        sheet = sheet,
+                        roll = rollAction,
+                    )
+
                     val success = rollStep?.let {
                         when (roll) {
                             in it.criticalSuccess -> getString(resource = Res.string.roll_page__critical_success)
diff --git a/composeApp/src/commonTest/kotlin/com/pixelized/desktop/lwa/parser/ArithmeticParserTest.kt b/composeApp/src/commonTest/kotlin/com/pixelized/desktop/lwa/parser/InstructionParserTest.kt
similarity index 90%
rename from composeApp/src/commonTest/kotlin/com/pixelized/desktop/lwa/parser/ArithmeticParserTest.kt
rename to composeApp/src/commonTest/kotlin/com/pixelized/desktop/lwa/parser/InstructionParserTest.kt
index 34729f2..9629dcc 100644
--- a/composeApp/src/commonTest/kotlin/com/pixelized/desktop/lwa/parser/ArithmeticParserTest.kt
+++ b/composeApp/src/commonTest/kotlin/com/pixelized/desktop/lwa/parser/InstructionParserTest.kt
@@ -1,12 +1,11 @@
 package com.pixelized.desktop.lwa.parser
 
-import com.pixelized.desktop.lwa.parser.arithmetic.Arithmetic
-import com.pixelized.desktop.lwa.parser.arithmetic.ArithmeticParser
 import com.pixelized.desktop.lwa.parser.arithmetic.Instruction
+import com.pixelized.desktop.lwa.parser.arithmetic.ArithmeticParser
 import kotlin.test.Test
 import kotlin.test.assertFails
 
-class ArithmeticParserTest {
+class InstructionParserTest {
 
     @Test
     fun testDiceInstructionParse() {
@@ -14,16 +13,16 @@ class ArithmeticParserTest {
 
         fun test(
             instruction: String,
-            expectedModifier: Instruction.Dice.Modifier?,
+            expectedModifier: Instruction.Dice.Modifier.Dice.Modifier?,
             expectedQuantity: Int,
             expectedFaces: Int,
         ) {
             val dice = parser.parseInstruction(instruction = instruction)
 
-            assert(dice is Instruction.Dice) {
+            assert(dice is Instruction.Dice.Dice) {
                 "Instruction should be ArithmeticInstruction.Dice but was: ${dice::class.java.simpleName}"
             }
-            (dice as? Instruction.Dice)?.let {
+            (dice as? Instruction.Dice.Dice)?.let {
                 assert(dice.modifier == expectedModifier) {
                     "$instruction modifier should be:\"$expectedModifier\", but was: ${dice.modifier}"
                 }
@@ -69,10 +68,10 @@ class ArithmeticParserTest {
         ArithmeticParser.words.map { instruction ->
             val word = parser.parseInstruction(instruction = instruction)
 
-            assert(word is Instruction.Word) {
+            assert(word is Instruction.Word.Word) {
                 "Instruction should be ArithmeticInstruction.Word but was: ${word::class.java.simpleName}"
             }
-            (word as? Instruction.Word)?.let {
+            (word as? Instruction.Word.Word)?.let {
                 assert(it.name == instruction) {
                     "Instruction should be $instruction, but was ${it.name}"
                 }
@@ -87,10 +86,10 @@ class ArithmeticParserTest {
         "100".let { instruction ->
             val flat = parser.parseInstruction(instruction = instruction)
 
-            assert(flat is Instruction.Flat) {
+            assert(flat is Instruction.Flat.Flat) {
                 "Instruction should be ArithmeticInstruction.Flat but was: ${flat::class.java.simpleName}"
             }
-            (flat as? Instruction.Flat)?.let {
+            (flat as? Instruction.Flat.Flat)?.let {
                 assert("${it.value}" == instruction) {
                     "Instruction should be $instruction, but was ${it.value}"
                 }
@@ -113,7 +112,7 @@ class ArithmeticParserTest {
         val parser = ArithmeticParser()
 
         fun test(
-            arithmetics: Arithmetic,
+            arithmetics: Instruction,
             expectedSign: Int,
             expectedInstruction: Instruction,
         ) {