Consisting of nothing but a solid sea of black ice, a frozen pearl formed from the endless streams pouring from the tunnels to Porphatys, Agathys the Ice-Bound is the deepest of Carceri's layers. Here, the orbs are so distant that not even a glimmer of light from the nearest can be seen, the sky consisting of nothing but an undifferentiated expanse of red. It's believed that Agathys may in fact consist of only a single tremendous orb, though no one has yet confirmed this either true or false. Agathys is the layer of false friendships and betrayers of confidence, and the weather reflects this, frigid like the cold hearts of its occupants. The air on Agathys is so rarefied and so cold that it's almost hard to breath, stinging the lungs and forcing people to struggle for breath (1d2 points of cold damage a round, DC 10 Con check once an hour to avoid fatigue).
Of course, beyond the temperature, the ice itself is the same acidic water found throughout the plane; eating it is very much not recommended. It seems eager to consume those that enter, with people spending too much time standing in a single place soon finding the ice inching its way around them. All about the layer can be seen body parts jutting from the surface, half-enveloped bodies of petitioners calling out with promises of alliances should they be released; alliances often (but not always) quickly broken at the first opportunity of escape from the plane. Those petitioners that spend enough time here and that accept their fate will soon adjust to life on Agathys through thick layers of blubber, quick to slough off and regrow should the ice begin to encroach on their bodies. These petitioners prefer pure solitude just as the orb itself, reacting quite violently to any that attempt to intrude on their privacy.
Many ancient writings from the yugoloths, from the days when the baernaloths were still present, hint that great secrets relating to the gehreleth can be found buried in the depths of Agathys's ice. Even that long-absent Apomps himself, father of the gehreleths, still resides within the frozen tunnels, dwelling at the center of Agathys. While it's unlikely that any could ever encounter Apomps here and live to tell the tale, many have tried; unsurprisingly, none yet that have returned have discovered anything of the kind.
- Manual of the Planes, 3rd edition, pp.107-108
- Planes of Conflict - Liber Malevolentiae, pg.23