Remove Ability when unit morphs

[roaaaarrrr]

I have a immolation item that is created by triggers. The issue is that every once in awhile, the ability gets stuck on permanently, when it is only supposed to last a certain number of seconds. This always happens during some sort of morph (alchemist to chemical rage, dh to meta, etc, etc). So is there a way in JASS to detect when a unit morphs? I just need to add this to my OnDestroy trigger and the ability will go away any time a unit morphs forms. This is the OnDestroy trigger if that helps...

   method onDestroy takes nothing returns nothing
        call ReleaseTimer(.t)
        call .removeUnitList()
        if .empty(.u) or IsUnitInvincible(.u) or  then
            call UnitRemoveAbility(.u,AbilityId)
        endif 
        set .u=null
    endmethod

 

[Laiev]

some (or most) of morphs use buff, check the buff
or when you cast the ability which morph set a boolean to true and check that boolean