Nion

Eminence — As long as Nion is in the command
zone or on the battlefield, you may cast spells from
your graveyard with mana value less than the
number of tax counters on it.
At the beginning of your upkeep, sacrifice Nion
unless you pay {u}{b}{r}{g}.
Counters remain on Nion as it moves to any zone.
When Nion leaves the battlefield, you may place it
in the command zone with a tax counter on it. You
may cast it from the command zone, it costs {2} more to cast for each tax counter on i