Acid Attacks and Acid Immunity - Vanilla-Expanded/VanillaExpandedFramework GitHub Wiki
A new Hediff, Hediff_AcidBuildup, has been added to provide acid attacks that cause extra damage over time. This hediff can be applied to any DamageDef by referring to it by its defName, "VEF_AcidBuildup". This hediff will then create additional acid burns for a while.
<DamageDef>
<defName>MM_AcidicBreath</defName>
<label>acidic breath</label>
<workerClass>DamageWorker_AddInjury</workerClass>
<externalViolence>true</externalViolence>
<hediff>VEF_AcidBurn</hediff>
<defaultDamage>1</defaultDamage>
<deathMessage>{0} has been poisoned to death.</deathMessage>
<additionalHediffs>
<li>
<hediff>VEF_AcidBuildup</hediff>
<severityPerDamageDealt>0.01</severityPerDamageDealt>
<victimSeverityScaling>ToxicSensitivity</victimSeverityScaling>
</li>
</additionalHediffs>
<harmAllLayersUntilOutside>true</harmAllLayersUntilOutside>
<armorCategory>Heat</armorCategory>
</DamageDef>
There is also a very very simple comp class that can be added to a creature to make it immune to this extra damage.
You can either use it like shown above, or assign the AnimalBehaviours.Hediff_AcidBuildup to one of your own hediffs. In any case the Hediff_AcidBuildup class will always cause addditional VEF_AcidBurn wounds, since the call to them is hardcoded.
To add the comp to make an animal immune to this just add:
<comps>
<li Class="AnimalBehaviours.CompProperties_AcidImmunity">
</li>
</comps>