One of the fun things about Dungeons & Dragons is its system of other realities. Apart from the world you play in (often termed the “Prime Material Plane”), you have a selection of Inner Planes, Outer Planes, Transitive Planes, alternate realities, and other random planes that seemed like a good idea at the time. All of these give a lot of adventuring opportunities for players and DMs.

In the early days of the game, a system of Outer Planes was devised, which was where the souls of the dead went after they died, and where the gods and their servants resided – as well as numerous other beings. This system was based on the alignment system of the time – with a plane for each combination of Law, Chaos, Good and Evil – thus, a total of nine outer planes, including the Neutral planes. (Lawful Neutral, True Neutral, etc.)

Except there weren’t nine planes – there were seventeen! Additional outer planes were used for characters that weren’t quite fully one alignment. There was a plane for beings that were Lawful, but half-way between Good and Neutral, and a plane for beings that were Good, but half-way between Lawful and Neutral. I’ve never been sure if this was to use all the names for other planes we have from the world’s mythology, or because Gary Gygax and his friends thought having half-way planes was good for the game. In many cases, players tend to focus only on the interesting planes and ignore the rest. Bytopia? The plane of Lawful Good Neutrals? That doesn’t see use that often! (It was originally called Arcadia, by the way!)

Despite calling them “planes”, each of the Outer Planes tends to be made of multiple layers – each its own plane, as far as I can gather, though sharing various features with the other layers of its Outer Plane.

The plane of absolute Lawful Evil is known as the Nine Hells of Baator, and it is there that devils reside. Each layer is ruled by an Archdevil, which have a complex set of allegiances that ultimately flow through to the ruler of the ninth hell – Asmodeus. It’s impossible to reach the lower layers of Hell without first entering the top layer. That layer? Its name is Avernus.

Avernus is ruled by the archduchess Zariel, a fallen angel. She took over the throne from the Archdevil Bel, who fell out of favour with Asmodeus. In the nature of Lawful Evil devils, Bel has been forced to serve Zariel as an advisor, but I wouldn’t be surprised if adventuring parties might be able to find the previous archdevil is scheming against his current mistress, seeking to become the lord of Avernus again. Or perhaps Bel will betray the adventurers to curry favour. Devils keep their words (Lawful!), but you have to be careful that the bargain you strike is the one you expect!

Avernus is also notable for being the place where Tiamat, Queen of Evil Dragons is imprisoned. I don’t know when or how Tiamat was imprisoned – it’s a mystery that began with the start of this edition of D&D. Her attempt to break free was detailed in the Tyranny of Dragon storyline – Hoard of the Dragon Queen and The Rise of Tiamat – two of my favourite adventures for this edition. Tiamat is served by the Abishai, strange draconic devils.

In Forgotten Realms lore, followers of Bane, the god of strife, opened a gateway to Avernus in the elven city of Myth Drannor. The city was ruined at the time – due to invasions and various factions fighting over its wealth – but the Banites thought that having a portal there would give them an easy source of allies to fight the other factions. Unfortunately for all concerned, the gate was stuck open, allowing devils to flood the city. Eventually, it was closed by the Knights of Myth Drannor, although devils still remained in the city.

Another portal to Avernus was created in Dragonspear Castle; it should be closed now, but you never know. Whether any lingering portal remains at the Well of Dragons to Tiamat’s prison is also unknown.

Avernus itself has been described as a rocky wasteland, with glowing spheres of light hanging in the air (and occasionally bursting into fireballs), inhabited by devils who are out of favour in the deeper hells. The River Styx flows through the layer, as it does all of the lower (evil) planes, and tributaries flow down to the deeper layers of Hell itself. Great armies of devils gather here for sorties against the demons and yugoloths of the other lower planes.

How true any of that is for this edition? I guess we’ll discover that in Baldur’s Gate: Descent into Avernus, when it’s released in a few months!