The Showstopper

Equip {x}
Equipped creature gains +X/+0 and gets Trample, Reach, and Double Strike.
When Equipped creature attacks, tap it. It doesn't untap during your next untap step.
"Someone once said that the best weapon is one you
never have to fire. Personally, I think that's bull. In
MY opinion, the best weapon is the weapon you only
have to fire ONCE." — Mr. Stark