diff --git a/app/imports/api/engine/computation/buildComputation/linkTypeDependencies.js b/app/imports/api/engine/computation/buildComputation/linkTypeDependencies.js
index 0acaf4cc..72add806 100644
--- a/app/imports/api/engine/computation/buildComputation/linkTypeDependencies.js
+++ b/app/imports/api/engine/computation/buildComputation/linkTypeDependencies.js
@@ -14,7 +14,7 @@ const linkDependenciesByType = {
   effect: linkEffects,
   proficiency: linkProficiencies,
   roll: linkRoll,
-  slot: linkSlot,
+  propertySlot: linkSlot,
   skill: linkSkill,
   spell: linkAction,
   spellList: linkSpellList,
diff --git a/app/imports/api/engine/computation/computeComputation/computeByType.js b/app/imports/api/engine/computation/computeComputation/computeByType.js
index cba44f28..b6ccff38 100644
--- a/app/imports/api/engine/computation/computeComputation/computeByType.js
+++ b/app/imports/api/engine/computation/computeComputation/computeByType.js
@@ -2,7 +2,7 @@ import _variable from './computeByType/computeVariable.js';
 import action from './computeByType/computeAction.js';
 import attribute from './computeByType/computeAttribute.js';
 import skill from './computeByType/computeSkill.js';
-import slot from './computeByType/computeSlot.js';
+import propertySlot from './computeByType/computeSlot.js';
 import container from './computeByType/computeContainer.js';
 import _calculation from './computeByType/computeCalculation.js';
 
@@ -13,6 +13,6 @@ export default Object.freeze({
   attribute,
   container,
   skill,
-  slot,
+  propertySlot,
   spell: action,
 });
diff --git a/app/imports/api/engine/computation/computeComputation/computeByType/computeSlot.js b/app/imports/api/engine/computation/computeComputation/computeByType/computeSlot.js
index 654655ba..9e9dc07b 100644
--- a/app/imports/api/engine/computation/computeComputation/computeByType/computeSlot.js
+++ b/app/imports/api/engine/computation/computeComputation/computeByType/computeSlot.js
@@ -1,6 +1,6 @@
 export default function computSlot(computation, node){
   const prop = node.data;
-  if (prop.quantityExpected){
-    prop.spaceLeft = prop.quantityExpected - prop.totalFilled;
+  if (prop.quantityExpected && prop.quantityExpected.value){
+    prop.spaceLeft = prop.quantityExpected.value - prop.totalFilled;
   }
 }
diff --git a/app/imports/ui/creature/slots/SlotFillDialog.vue b/app/imports/ui/creature/slots/SlotFillDialog.vue
index 6d67cc21..c5c0180d 100644
--- a/app/imports/ui/creature/slots/SlotFillDialog.vue
+++ b/app/imports/ui/creature/slots/SlotFillDialog.vue
@@ -188,6 +188,8 @@ import LibraryNodes from '/imports/api/library/LibraryNodes.js';
 import DialogBase from '/imports/ui/dialogStack/DialogBase.vue';
 import TreeNodeView from '/imports/ui/properties/treeNodeViews/TreeNodeView.vue';
 import PropertyDescription from '/imports/ui/properties/viewers/shared/PropertyDescription.vue'
+import resolve, { toString } from '/imports/parser/resolve.js';
+import { prettifyParseError, parse } from '/imports/parser/parser.js';
 // import evaluateString from '/imports/api/creature/computation/afterComputation/evaluateString.js';
 import getSlotFillFilter from '/imports/api/creature/creatureProperties/methods/getSlotFillFilter.js'
 import Libraries from '/imports/api/library/Libraries.js';
@@ -291,8 +293,9 @@ export default {
         return CreatureProperties.findOne(this.slotId);
       } else if (this.dummySlot) {
         let model = clone(this.dummySlot)
-        model.quantityExpectedResult = +model.quantityExpected;
-        model.spaceLeft = model.quantityExpectedResult;
+        if (!model.quantityExpected) model.quantityExpected = {};
+        model.quantityExpected.value = +model.quantityExpected.calculation;
+        model.spaceLeft = model.quantityExpected.value;
         return model;
       }
     },
@@ -342,7 +345,7 @@ export default {
       return quantitySelected;
     },
     spaceLeft(){
-      if (this.model.quantityExpectedResult === 0) return undefined;
+      if (!this.model.quantityExpected || this.model.quantityExpected.value === 0) return undefined;
       return this.model.spaceLeft - this.totalQuantitySelected;
     },
     libraryNames(){
@@ -360,13 +363,23 @@ export default {
       // the quantity to fill
       nodes.forEach(node => {
         if (node.slotFillerCondition){
-          let {result} = evaluateString({
-            string: node.slotFillerCondition,
-            scope: this.creature.variables,
-            fn: 'reduce',
-          });
-          if (!result.value){
+          try {
+            let parseNode = parse(node.slotFillerCondition);
+            const {result: resultNode} = resolve('reduce', parseNode, this.creature.variables);
+            if (resultNode?.parseType === 'constant'){
+              if (!resultNode.value){
+                node._disabledBySlotFillerCondition = true;
+                disabledNodeCount += 1;
+              }
+            } else {
+              node._disabledBySlotFillerCondition = true;
+              node._conditionError = toString(resultNode);
+              disabledNodeCount += 1;
+            }
+          } catch (e){
+            let error = prettifyParseError(e);
             node._disabledBySlotFillerCondition = true;
+            node._conditionError = error;
             disabledNodeCount += 1;
           }
         }
diff --git a/app/imports/ui/creature/slots/Slots.vue b/app/imports/ui/creature/slots/Slots.vue
index 3b505451..cf5570d9 100644
--- a/app/imports/ui/creature/slots/Slots.vue
+++ b/app/imports/ui/creature/slots/Slots.vue
@@ -8,8 +8,8 @@
       <h3 class="layout align-center">
         {{ slot.name }}
         <v-spacer />
-        <span v-if="slot.quantityExpectedResult > 1">
-          {{ slot.totalFilled }} / {{ slot.quantityExpectedResult }}
+        <span v-if="slot.quantityExpected && slot.quantityExpected.value > 1">
+          {{ slot.totalFilled }} / {{ slot.quantityExpected.value }}
         </span>
       </h3>
       <v-list v-if="slot.children.length">
@@ -37,7 +37,7 @@
         </v-list-item>
       </v-list>
       <v-btn
-        v-if="!slot.quantityExpectedResult || slot.spaceLeft"
+        v-if="!slot.quantityExpected || !slot.quantityExpected.value || slot.spaceLeft"
         icon
         :data-id="`slot-add-button-${slot._id}`"
         class="slot-add-button"
@@ -120,8 +120,8 @@ export default {
         'ancestors.id': this.creatureId,
         type: 'propertySlot',
         $or: [
-          {slotConditionResult: {$nin: [false, 0, '']}},
-          {slotConditionResult: {$exists: false}},
+          {'slotCondition.value': {$nin: [false, 0, '']}},
+          {'slotCondition.value': {$exists: false}},
         ],
         removed: {$ne: true},
         inactive: {$ne: true},
@@ -130,7 +130,7 @@ export default {
       }).map(slot => {
         if (
           !this.showHiddenSlots &&
-          slot.quantityExpectedResult === 0 &&
+          (slot.quantityExpected && slot.quantityExpected.value) === 0 &&
           slot.hideWhenFull
         ){
           slot.children = []
@@ -146,7 +146,7 @@ export default {
       }).filter(slot => !( // Hide full and ignored slots
         !this.showHiddenSlots && (
           slot.hideWhenFull &&
-          slot.quantityExpectedResult > 0 &&
+          (slot.quantityExpected && slot.quantityExpected.value) > 0 &&
           slot.spaceLeft <= 0 ||
           slot.ignored
         )
diff --git a/app/imports/ui/properties/viewers/shared/PropertyDescription.vue b/app/imports/ui/properties/viewers/shared/PropertyDescription.vue
index d70969f1..5763d24d 100644
--- a/app/imports/ui/properties/viewers/shared/PropertyDescription.vue
+++ b/app/imports/ui/properties/viewers/shared/PropertyDescription.vue
@@ -1,6 +1,6 @@
 <template lang="html">
   <markdown-text
-    v-if="text"
+    v-if="text && model"
     :markdown="model.value || model.text"
   />
   <property-field