Ally, Ambyrblood Child

Indestructible
If you would take combat damage, you instead
exile that many cards from the top of your
library and place a force counter on Ally,
Ambyrblood Child. Then, if there are three or
more force counters on Ally, Ambyrblood Child, sacrifice it and deal damage to target creature
equal to the number of cards exiled by Ally, Ambyrblood Child.