Cumulative upkeep(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 or when Tombstone Stairwell leaves the battlefield, destroy all tokens created with Tombstone Stairwell. They can't be regenerated.
10/4/2004 All the tokens are put onto the battlefield simultaneously.
10/4/2004 Both the cumulative upkeep and the triggered ability trigger at the beginning of upkeep, so you can choose what order they resolve.
10/4/2004 You control the triggered ability, but each player controls the token creature they put onto the battlefield due to the ability’s effect.
10/4/2004 Does not put the Zombies onto the battlefield if this card is not still on the battlefield when its ability resolves.
10/4/2004 If something changes the names of the tokens, then the “at end of turn” ability will still destroy them.
10/1/2008 This has the supertype world. When a world permanent enters the battlefield, any world permanents that were already on the battlefield are put into their owners’ graveyards. This is a state-based action called the “world rule.” The new world permanent stays on the battlefield. If two world permanents enter the battlefield at the same time, they’re both put into their owners’ graveyards.