To play with Disasters, Eldritch Tokens are set up on the Ancient One's track on specific numbers specified on the Ancient One sheet or the Prelude. Whenever Doom advances to a position on the Doom Track with an Eldritch Token on it, the investigators draw one random Disaster, resolve its effects, then discard the Eldritch Token on the track. Other cards like Mythos cards or the backs of Conditions might also cause a Disaster.
If more than one Disaster occurs at the same time, completely resolve one Disaster before resolving the next.
Some Disasters will cause Devastation to occur on a space, and some will not. If all nine major cities are devastated, the players immediately lose the game.