Aqua

When this card is summoned equip it to a land. That land becomes a creature "Aqua" with X/X, where X is the number of islands in play.
It is also still an island
Aqua gains the following effects: Trample, hex-proof.
Aqua can only attack opponents if they control an island.
Aqua can not be destroyed or exiled, if it would
be destroyed or exiled then tap it for three turns, during this time it can not be untapped.