Mirage

Tombstone Stairwell

Cumulative upkeep o1o
B
During each upkeep, each player puts into play a Tombspawn token for each summon card in his or her graveyard. Treat these tokens as 2/2 black creatures that are unaffected by summoning sickness and count as Zombies. At end of any turn or if Tombstone Stairwell leaves play, bury all of these tokens.

Cumulative upkeep {1}{B} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
At the beginning of each upkeep, if Tombstone Stairwell is on the battlefield, each player creates a 2/2 black Zombie creature token with haste named Tombspawn for each creature card in their graveyard.
At the beginning of each end step and when Tombstone Stairwell leaves the battlefield, destroy all tokens created with Tombstone Stairwell. They can't be regenerated.