Ah, I see the confusion
I was saying that if the "deal damage to opponent equal to target's max hp" clause creates a long lasting status effect... i.e. if you kill it later that turn it triggers, then the card is too powerful with a catapult combo.
For instance, flown titan + bb + catapult + this = OTK for a 4 card combo and 1
+ 5
+ 1
+ 4
+ 2
so otk for 13
and 4 cards in a trio.
That seems a little on the strong side to me.
On the other hand, if the effect only triggers if the spell itself kills the target, then this card is a little UP... or at least very situational.
It really only becomes valuable against very high HP creatures... which take a lot of work to bring down in the first place.
And as you mention, its lowsy as a CC right now.