Aukarius of the Deep

Whenever you cast a legendary merfolk creature,
reveal the top cards of your library until you
reveal a land. If the land is an island you may put
it on the battlefield tapped, otherwise put it in
your hand. Put the remaining revealed cards on
the bottom of your library in a random order.
At the beginning of your upkeep, each player
mills cards equal to the number of merfolk
creature cards in your graveyard.