Wanderwine Prophets triggers, sacrificing itself and causing you to take an extra turn after this one.
When
Wanderwine Prophets dies, it triggers, returning all cards exiled with it to the battlefield.
Cast
Wanderwine Prophets from your graveyard for its retrace cost by paying ({4} magic symbol) ({U} magic symbol) ({U} magic symbol) and discarding a land card.
When
Wanderwine Prophets enters the battlefield, it triggers, exiling another Merfolk you control.
Move to your next turn.
During your draw step, choose to reveal cards from the top of your library until you reveal a land card and put it into your hand.
Repeat.
Notes
You may execute this combo by sacrificing another Merfolk instead of
Wanderwine Prophets. This changes the mana needed each turn to that Merfolk's casting cost. You may then ignore steps 3 and 5.