The Mighty Swamp

{t}: add {b} to your mana pool
{t}: add a counter to The Mighty Swamp
{b}{b} {t}: Add one {b} to your mana pool for each counter on The Mighty Swamp.
{b}{b} {t}: Remove {x} counters from The Mighty Swamp: Add {x} in any combination to your mana pool. Use this mana only on spells that cost {x}