Special room (dNethack)
The marked Z is a Dread Seraph. For most of the game, Dread Seraphs will lie dormant in their sepulchers, though there presence on a level causes corpses to rise from the dead as zombies or skeletons. When the character visits a level containing a sepulcher and has the Amulet or has killed The Wizard, the Seraph will wake up.
Sepulchers are undiggable and un-phaseable. They are also only generated below level 13.
Magic Item Vault
dNethack adds a separate type of vault, similar to gold-containing vanilla vaults. They contain monsters to guard the treasure inside 4 chests. Each chest contains 2-8 (2d4) magic items (25% of which will be a random piece of magic armor, the other 75% of which will be any magical item). It's possible, albeit with the same chance as any other item, for the chests to contain artifacts. Any artifact that cannot be put into a container will not be generated however. Additionally, extra chests with normal chest items may be generated in each square.
Vaults will contain a random monster chosen from the below list (each has equal probability):
- Priest of Ghaunadaur
- Eye of doom
- Son of Typhon
- Dark young
- Mirkwood elder
- Purple worm
- Hunting horror
- Gigantic pseudodragon
- Id juggernaut
- Scrap titan
- Hellfire colossus
- Guardian naga
- Grove guardian
- Iron golem
Gardens are rooms with nymphs, plants, trees or fountains, and possibly a weeping angel. Up to 4 nymphs are generated, 3-5 plants of any kind, 3 trees of fountains, and a 50% of a weeping angel.
Library (otherwise known as Waterlogged Library)
Libraries are generally small rooms, with living lecterns, pools or fountains, and walls containing spellbook. Up to 3 fountains/pools are placed, and up to 4 living lecterns. Every wall square contains either a spellbook of blank paper (1/6 chance) or a random other spellbook.
Rivers aren't special "rooms" per se, but they are generated the same way. Rivers can be generated anywhere. With a 1/4 chance, the river will run horizontally, otherwise vertically. Rivers are guaranteed never to block your path to any room (a trail of floor will be left where the river would be blocking). They can spawn sea monsters and kelp fronds just like other water.
Islands are similar to gardens, but contain a moat of water along the inside wall. (if below level 12, lava may be present instead) They also contain a square marked "X" with a chest of treasure (gold) buried underneath it. One lone tree is always next to the X.
Various properties of islands are as follows:
- Stairs will never be generated inside the island, to prevent characters from leaving the level or room.
- A one-door room ensures this room isn't a necessary juncture between staircases.
- Deeper in the dungeon (past the mines, certainly) it becomes less likely that the player will be held back by a single room, so beyond level five the restrictions are relaxed a bit. (the room can have two doors)
- In case the player teleports into the room or falls into it from above, a trap door is always generated inside it so the player can escape.
- If we're on or before level four, island rooms can only be made in the same kinds of places as shops. (they are thus much rarer)
- Starting with level six, if the room is big enough there may be some more water.
- Below level nine, a sea monster may be generated in the moat.
Throne Room (Throne Occupied)
Unlike in vanilla, dNethack throne room monsters are often (75%) themed after a specific ruler. Ruler types and corresponding monsters are, in a roughly sorted level of difficulty:
- Kobold lord (difficulty 3): Kobold shaman, large kobold, kobold, lemure, imp.
- Gnome king/Gnome queen (difficulty 6): Gnome lord, gnome lady, gnome, gnomish wizard, tinker gnome, dwarf, dwarf lord, dwarf cleric, hobbit, leprechaun, homunculus.
- Orc captain (difficulty 7): Orc shaman, mordor orc, hill orc, hobgoblin, goblin, manes, quasit.
- Dwarf king/Dwarf queen (difficulty 8): Dwarf lord, dwarf cleric, dwarf, gnome, gnome lord, gnome lady, gnomish wizard, hobbit, leprechaun.
- Ogre king (difficulty 11): Ogre mage, ogre lord, ogre, orc captain, mordor orc, tengu, troll, random H.
- Elvenking/Elvenqueen (difficulty 14): Elf lord, elf lady, grey elf, green elf, woodland elf, quickling, dryad, naiad, coure eladrin, noviere eladrin, bralani eladrin, firre eladrin, shiere eladrin, doppelganger, wood troll.
- Vampire lord (difficulty 14): Vampire, random Z, random M, flesh golem, werewolf, floating eye, gargoyle, winged gargoyle, quasit, black pudding, wraith, phantasm, ghost, maid, weeping willow, swamp nymph.
- Drow matron (difficulty 15): Unearthly drow, hedrow wizard, hedrow warrior, drow, sprow, swamp nymph, giant spider, cave lizard, large cave lizard, quasit.
- Titan (difficulty 20): Storm giant, fire giant, frost giant, hill giant, stone giant, giant, son of Typhon, dryad, naiad, oread, deminymph.
- Embraced drowess (difficulty 27): Drow alienist, hedrow blademaster, edderkop, hedrow wizard, hedrow warrior, drow mummy.
- Deepest one (difficulty 33): Deeper one, deep one, human, mind flayer, dark young, umber hulk, stumbling, wandering, and shambling horrors.
- Orc of the ages of stars (difficulty 37): Deep wyrm, red dragon, white dragon, black dragon, blue dragon, angband orc, hedrow blademaster, succubus, incubus, olog-hai, siege ogre, hell hound.
Rulers are chosen according to their difficulty. The chosen ruler will not have a difficulty greater than the average of your level and the dungeon level difficulty + 5, and will not be lower than 2/3 of the dungeon level difficulty. If no prospective ruler fits these criteria, dNethack will fall back on the standard set of throne room monsters.