If Cthulhu (Hoary Wings) is in play:

Resolve Cthulhu's patrol keyword an additional time.

If Cthulhu (Fierce Visage) is in play:

The nearest investigator to Cthulhu must test (X), where X is Cthulhu's Rage. If that investigator fails, Cthulhu (Fierce Visage) attacks them.

If Cthulhu (Wicked Claw) is in play:

Choose an investigator at Cthulhu's location to test (X), where X is Cthulhu's Rage. If that investigator fails, they must either increase the flood level of Cthulhu's location, or take 1 damage or 1 horror.