Tombstone Stairwell

Cumulative upkeep {1}{b}
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
or when Tombstone Stairwell leaves the battlefield, destroy all tokens created with
Tombstone Stairwell. They can't be regenerated.