The Mind Flayer

{1}{u}{u}{b}, {t}: Gain control of target creature
with power less than or equal to The Mind
Flayers power.
At the beginning of combat on your turn, you
may sacrafice a creature you control but don't
own. If you do, put X +1/+1 counters on
The Mind Flayer, where X was the sacrafice creatures power. Otherwise, tap The Mind
Flayer.