Added a hpDamageTkenMultiplier rule active effects can modify to multiply the total damage an actor takes from others

module/data/actor/base.mjs

@@ -51,6 +51,11 @@ export const commonActorRules = (extendedData = { damageReduction: {}, attack: {
                 nullable: false,
                 initial: 1
             }),
+            hpDamageTakenMultiplier: new fields.NumberField({
+                required: true,
+                nullable: false,
+                initial: 1
+            }),
             ...(extendedData.attack?.damage ?? {})
         })
     })

module/data/fields/action/damageField.mjs

@@ -106,16 +106,18 @@ export default class DamageField extends fields.SchemaField {
                     actor.takeHealing(config.damage).then(updates => targetDamage.push({ token, updates }))
                 );
             else {
+                const configDamage = foundry.utils.deepClone(config.damage);
                 const hpDamageMultiplier = config.actionActor?.system.rules.attack.damage.hpDamageMultiplier ?? 1;
-                if (config.damage.hitPoints) {
-                    for (const part of config.damage.hitPoints.parts) {
-                        part.total = part.total * hpDamageMultiplier;
+                const hpDamageTakenMultiplier = actor.system.rules.attack.damage.hpDamageTakenMultiplier;
+                if (configDamage.hitPoints) {
+                    for (const part of configDamage.hitPoints.parts) {
+                        part.total = part.total * hpDamageMultiplier * hpDamageTakenMultiplier;
                     }
                 }
 
                 damagePromises.push(
                     actor
-                        .takeDamage(config.damage, config.isDirect)
+                        .takeDamage(configDamage, config.isDirect)
                         .then(updates => targetDamage.push({ token, updates }))
                 );
             }

src/packs/adversaries/adversary_Jagged_Knife_Kneebreaker_CBKixLH3yhivZZuL.json

@@ -336,7 +336,14 @@
               "range": "melee"
             }
           },
-          "changes": [],
+          "changes": [
+            {
+              "key": "system.rules.attack.damage.hpDamageTakenMultiplier",
+              "mode": 5,
+              "value": "2",
+              "priority": null
+            }
+          ],
           "disabled": false,
           "duration": {
             "startTime": null,
@@ -350,8 +357,8 @@
           "description": "",
           "tint": "#ffffff",
           "statuses": [
-            "restrained",
-            "vulnerable"
+            "vulnerable",
+            "restrained"
           ],
           "sort": 0,
           "flags": {},