Derelict Power Plant

Derelict Power Plant enters the battlefield
tapped with a charge counter on it for each mana
used to pay X.
{t}: Add {c} or {r} to your mana pool.
{t}: Remove a charge counter from Derelict
Power Plant. Add {c}{r}{w}{g} to your mana pool.
"Some old-world relics are just empty shells of what
they were, while others still retain the power of their
true selves."