Man-Eater Bug

Flip (You may cast this face down and tapped as a
1/1 creature for its casting cost. Turn it face up when
it blocks or when it untaps. Additionally, this
creature may block while tapped. If it blocks in this
way, it assigns combat damage equal to its toughness
rather than its power.)
When Man-Eater Bug is turned face up, destroy
target creature.