At the beginning of your upkeep, if Nyarlathotep is in the graveyard, in exile, or on the battlefield, you may have Nyarlathotep become a copy of any creature on the battlefield, except its name is still Nyarlathotep, it's legendary in addition to its other types, and it gains "You may cast this spell from your graveyard or from exile." and this ability.
During each of target players upkeep, that player may pay
, where X is the number of chaos counters on Nyarlathotep, the Crawling Chaos. If they do, put a chaos counter on Nyarlathotep, then destroy each other permanent with converted mana cost equal to the number of chaos counters on Nyarlathotep. Otherwise, that player sacrifices each permanent they control.
