Munch is the main timing check
Supreme Ant walks up and bites for 2 base damage. Its animation is faster than the ordinary Ant Army attack, so watch the boss’s mandibles rather than reusing the smaller enemy’s timing.
Call for Help
The summon requires an open enemy slot and can fail. When it fails, no add needs clearing: use the opportunity on the boss. When it succeeds, compare the add’s extra future actions with how close you are to ending the fight.
Location
The story encounter is at the Caves exit toward Roadtown. In Demo 5, Supreme Ant is on Pit Floor 17 with other enemies. Older floor-18 references predate Spiky Killbot moving into that floor.
Mechanics references: The Pit of 100 Trials