The chasme (greater tanar'ri) appeared in the Monstrous Compendium Volume Outer Planes Appendix (1991). The chasme (greater tanar'ri) also appeared in the first Planescape Monstrous Compendium Appendix (1994).
Chasmes are merciless demons resembling great flies. They enjoy torturing and tormenting other beings, also demons, especially if they are sure of their impunity. Because of their cruelty, chasmes are often charged with torturing enemies and deserters. Sometimes chasmes can be found in group acting as patrols; they fly in the skies of the Abyss looking for intruders[original research?].