Darth Bane

Menace, Trample
Whenever you control more than two Sith,
sacrifice Darth Bane.
At the beginning of your end step, if you control
exactly two Sith, you may put X -1/-1 counters
on target Sith you control, where X is that
creature's power. If you do, put X +1/+1
counters on another target Sith you control.
"There should only be two, no more, no less. One to
embody power, the other one to crave it."