Play with your hand revealed.
If you would draw a card, reveal the top card of your library instead. If it's a creature card, put it into your graveyard. Otherwise, draw a card.
Whenever a creature is put into your graveyard from the battlefield, return it to your hand.
Champion a Merfolk (When this enters, sacrifice it unless you exile another Merfolk you control. When this leaves the battlefield, that card returns to the battlefield.)
Whenever this creature deals combat damage to a player, you may sacrifice a Merfolk. If you do, take an extra turn after this one.