Bewitching Dryad

Bestow {5}{g}{g}
Enchanted creature has: "Cumulative upkeep:
Put a -1/-1 counter on this creature."
You control enchanted creature.
When enchanted creature dies, add {b} to your
mana pool for each -1/-1 counter on it. Until end
of turn, you don't lose this mana as steps and
phases end.