Obsidian, Ultimate Fusion

Haste, Reach, Vigilance, Gem Fusion (When
this enters the battlefield, sacrifice this unless you
exile two other Gems you control until this leaves
the battlefield. Put a +1/+1 counter on this for each
color it shares with those Gems.)
Whenever Obsidian, Ultimate Fusion attacks,
return target creature you don't control and up
to one target creature you control to their
owners' hands.