Flatlantis

Flatlantis comes into play untapped with a
firmament counter on it.
{t}: Add one mana of any color to your mana
pool. This can only be used if Flatlantis has a
dome counter on it.
{3}, {t}, Remove a dome counter from Flatlantis:
Add {w}{u}{b}{r}{g} to your mana pool. This mana
can only be used to cast your commander.