Merfolk Seamaker

Overdraw - {7}: Up to two mana in target player's mana pool becomes blue. Activate this ability only when an island enters the battlefield. (This ability costs {1} less to activate for each opponent.)
Overdraw - {6}: Create a 1/1 blue Elemental creature token with "At the beginning of your upkeep, if you don't control a card named 'Merfolk Seamaker', sacrifice this creature." Activate this ability for each blue mana spent
when an opponent spends blue mana.