Giant Droughtwurm

Emerge {u}-> {w} (When this spell is cast, if each
land you control is an island, sacrifice them and
search your library for that many basic plains.
Put them into play tapped, then shuffle your
library.)
When Giant Droughtwurm enters the
battlefield, if it emerged, Exile target
tapped creature. Tap target creature.
You gain 4 life.