Waterspell ponderer

Secluded (at the beginning of your upkeep
you may exile this creature under an island
or return this creature from exile if it is
secluded. If this creature is the only creature
exiled under an island it is "secluded").
Whenever you cast an instant or sorcery
spell while this creature is secluded create
a 1/1 blue elemental creature token.