Elstwere, Isle of Remembrance

Elstwere, Isle of Remembrance enters the battlefield tapped unless you control a Plains, a
Swamp, and a Forest.
{t}: Add {w}, {b}, or {g} to your mana pool.
{x}{b/g}{g/w}{w/b}{t}: Return an exiled nonland
permanent with mana value {x} to the battlefield
under your control.