Bahamut, Lord of Bevelle

Bahamut enters the battlefield tapped and with
X +1/+1 counters on it.
You may choose not to untap Bahamut during
your untap step. If you don't, gain an overdrive
counter. Then, if you have a number of overdrive counters equal to or greater than Bahamut's
power, lose all overdrive counters and Bahamut
deals damage equal to its power to each opponent
and each creature and planeswalker they control.