I just thought of this out of the blue and thought it would be pretty unique for a creature steal.
Pull of the Tides

Enchantment - Aura
Enchant Creature.
Affinity for Islands.
Enchanted creature has islandwalk.
The player who controls the most islands controls enchanted creature.
I'm really not sure on the formatting of the card and whatnot so lemme know.
Current Version:
Pull of the Tides

Enchantment - Aura
Enchant Creature.
Affinity for Islands.
Enchanted creature has islandwalk.
The player who controls the most islands controls enchanted creature.