Tombstone Stairwell
{2}{B}{B}
World Enchantment
Cumulative upkeep {1}{B} (At the beginning of your upkeep, put an age counter on ~this~, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
At the beginning of each upkeep, if ~this~ 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 ~this~ leaves the battlefield, destroy all tokens created with ~this~. They can't be regenerated.