Changeling Island

When Changeling Island enters the battlefield, choose a creature type, that creature type is a changeling in addition to its other types when not in play. When Changeling Island enters the battlefield, it enters tapped unless you control another Changeling Island.
{t} Add {c}{c} to your mana pool.
If you control a changeling, you may spend mana produced by any lands you control as if it were mana of any type to cast changeling spells.