Cumulative upkeep 1B
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.

NOTE: Stock image, not actual card.