Mind Crab

Whenever Mind Crab or another artifact you control becomes the target of a spell or ability, counter that spell or ability and draw a card.
Whenever Mind Crab becomes blocked, you may put target creature with converted mana cost 3 or less on top of its owners library. If you do, it assigns no combat damage this turn.
"You cannot harm us. Simply sit back and watch."
-Iruquos, Herald of the Crabs