Venom, Ravenous

Menace, Lifelink
Symbiote(When this enters the battlefield, sacrifice
this or exile another target creature you control until
this leaves the battlefield. If you exiled a creature this
way, for each color shared between these creatures,
put a +1/+1 counter on this. When the exiled creature
returns to the battlefield, put a -1/-1 counter on it for
each non-shared color between these creatures.)