Wailord

Islandwalk
Evolve {u}{u}{u}{u}(You may play this card for its
evolve cost by exiling a creature you control named
Wailmer. When Wailord leaves play put all cards
exiled by it in the graveyard.)
When Wailord enters the battlefield if it evolved
all basic lands become islands in addition to their
other types. Then exile all nonbasic land on the battlefield.