Grail Guardian

Flash
Chivalry(You may tap any number of human
creatures you control as you cast this spell. Put a
+1/+1 counter on each creature tapped this way.)
When Grail Guardian enters the battlefield, you
may tap or untap target creature.
It is our sacred duty to guard such an artifact, and in
such it is our decision to decide who is worthy of seeing
such a magnificent sight.