Kaisun, The Swimming Temple

Islandwalk, indestructible
When Kaisun enters the battlefield, if you control 7 or more islands, return all other creatures to their owners hand except turtles, fish, krakens, and octopuses. Then scry 2.
Whenever Kaisun attacks an opponent and becomes blocked, you may choose a land they control, this land becomes an island in addition to its other types.