Great Whale + Cavern Harpy + Panharmonicon

Great Whale

Cavern Harpy

Panharmonicon

How it works

1. Activate up to seven lands you control by tapping them, adding at least 2.
2. Cast Great Whale by paying 5.
3. Great Whale enters the battlefield, triggering its ability twice.
4. Resolve the first Great Whale trigger, untapping the seven lands.
5. Activate the seven lands by tapping them, adding at least 2.
6. Resolve the second Great Whale trigger, untapping the seven lands.
7. Cast Cavern Harpy by paying .
8. Cavern Harpy enters the battlefield, triggering its ability twice, returning Cavern Harpy and Great Whale from the battlefield to your hand.
9. Repeat.