Pygmy Hippo

Whenever Pygmy Hippo attacks and isn't blocked, you may have defending player play a mana ability of each land he or she controls and empty his or her mana pool. If you do, Pygmy Hippo deals no combat damage this turn and at the beginning of your postcombat main phase, you add to your mana pool, where X is equal to the amount of mana emptied from defending player's mana pool this way.