Stellar Obstructor

Stellar Obstructor does not untap during it's
controller's untap step.
{2}{w}{u}{t}: Place X charge counters on Stellar Obstructor where X is the amount of unspent
colored mana in your mana pool. Then your
mana pool is drained.
{2}{w}{u}{ut}: Remove all charge counters from
Stellar Obstructor. Add {1} to your mana pool
for each counter removed this way.