Tombstone Stairwell [Mirage] Core Set 2019 Promos the Su-Chi were inherently unstable

the Su-Chi were inherently unstable but provided useful knowledge for Tocasia's students

Exile the top six cards of your library

where X is its mana value

Change the text of target permanent by replacing all instances of one color word with another or one basic land type with another until end of turn

they have indestructible

Tombstone Stairwell [Mirage] Core Set 2019 Promos the Su-Chi were inherently unstableSet: Mirage Type: World Enchantment Rarity: Rare Cost: {2}{B}{B} 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