Krakoa

Krakoa comes into play tapped.
{t}: Add one mana of any color to your
mana pool.
{w}{u}{b}{r}{g}: Krakoa becomes a 5/5 mutant
creature with indestructible until end of
turn. It's still a land.
"Now you have Krakoa, and Krakoa is all you
will ever need." — Magneto