Better use immolation...
When it finishes casting(turning on) immolation, add a spellbook that contains the damage block abillity, and then disable it.ALSO, play unit's defend animation. For turning off : a unit is issued an order with no target
conditions : issued order equal to unimmolation
Actions for unimmolation : reset unit's animations. Remove the disabled spellbook.
That can be easy
OR, the saming things for defend. the issued order with no target is undefend for tuning off.
For defend/undefend, you mustn't use the action to play unit's animations.