On Radsworth's initiative (and unless he commands them to do otherwise), the two giant ants scurry from the stairwell around the corner, through the doorway into the chamber where an enlarged Derrik, and a confused Koran, stand before the alcove in the south wall, wherein the invisible Intellect Devourer hides....
The giant ants' feelers twitch excitedly, and their heads bob as they seem to be sniffing out the location of the invisible aberration....
Both make move actions into the north chamber and stop behind Derrik, barring any possible escape attempts the ID might attempt!