The Master Chief

Partner with Cortana, Compassionate A.I.

Reach, trample

At the beginning of your upkeep, if The Master Chief
does not have a shield counter, put a shield counter on
The Master Chief.

{w}{g}{g}, {t}: The Master Chief deals damage equal to its power to target creature or planeswalker an opponent controls. If a creature or planeswalker dies this way, untap The Master Chief.