Anakin Skywalker

Anakin can't block.
Dark Side(When Anakin attacks, he gets +X/-X
where X is the number of +1/+1 counters on
him.)
Enraged — Anakin Skywalker gets +2/+1
as long as Anakin is the only creature you control.
Whenever another creature you control dies, you
may put a +1/+1 counter on Anakin.