Slave-Knight Gael

Slave-Knight Gael enters the battlefield tapped
and doesn't untap during your untap step.
Sacrifice another creature: Untap Gael and put
a +1/+1 counter on it.
Whenever Gael attacks, destroy target creature defending player controls, then put a +1/+1
counter on Gael.
Gael knew that the dark soul would ruin him.