Mana Bloom
Mana Bloom enters the battlefield with X charge counters on it.
Remove a charge counter from Mana Bloom, add one mana of any color to your mana pool. Activate this ability once per turn.
At the beginning of your upkeep, if Mana Bloom has no charge counters on it, return Mana Bloom to your hand
This sounds awesome If only you could remove any number of counters a turn.