Go forth and aid the weak!
Henzell says...
  1. A merry-go-round of doom, featuring many, many, many different kinds of monsters who will find your flesh, bones, mind, and life tasty. 7 levels. Rune spawns in vaults on floor 3 and deeper.
  2. Before 0.29, Abyss was 5 levels deep. In 0.28+, random floor items no longer generate. In 0.28 only, you could not gain exploration/kill piety and monsters did not award xp here.
  3. When you get enough xp (roughly half the requirement for an elemental evocable), an exit from the abyss will open. Further kills generate more exits and stairs down (an exit if you're already on the deepest level; otherwise 50/50 exits and stairs).
  4. Exits can be found randomly. Converting to Lugonu will also let you get out, but be warned that divine retribution is typically of the same nastiness level as banishment.
  5. To get in, definitely: Fail your Will check against Banishment. Go down on a portal. Successfully invoke Lugonu's fifth power.
  6. To get in, maybe: Get hit by something with the distortion or chaos brand. Unwield distortion. Arouse the wrath of Lugonu or Nemelex. Attract the attention of Xom.
  7. <pwnmonkey> The abyss is like boris in level form
  8. <ktgrey> i wonder if everyone in the abyss, is there because they got banished to it <ktgrey> its like fantasy australia
  9. see {abyss guide}
  10. <elliott> dying is less painful than the abyss
    11. More...

Information based on master branch and the great LearnDB.
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