Poliwhirl

Put 3 damage counters on Poliwhirl. If this doesn't knock out Poliwhirl, search your deck for up to 2 Basic Energy cards and attach them to Poliwhirl. Shuffle your deck afterward.

Does 30 damage plus 10 more damage for each W Energy attached to Poliwhirl but not used to pay for this attack's Energy cost. You can't add more than 20 damage in this way.