Olgreb’s Hidden Sanctum
Mechanics: Players are permanently affected by rPois- status (like from a Naga Ritualist Virulence), all shallow water is toxic sludge instead (a la Noxious Bog). Makes it easy for non-living species and form users, but eh, it’s on theme for poison to be weak vs them. Also makes it easy if you’ve found Olgreb’s Staff beforehand, which is nice thematically (staff is the key and all that).
Enemies: Various mid-high tier swamp themed Spectral things outside of the building (bunyips, hydras, caustic shrikes). Inside - lots of Green Deaths, Orange Demons and some Cacodemons + special boss group. The challenge is to fight a bunch of poison demons in unpredictable terrain and without poison resistance.
Layout: Player enters in an open swamp (water is noxious bog) like area with mostly dead and some alive trees here and there. Spectres are wandering around. A narrow wobbly path through the swamp leads to a spherical or polyhedral dome of stone with a small entryway (no door). On the outside dome is overgrown with dead trees, it’s sort of jutting out of the dead forest (map edges are dead/alive forest as well).
Inside half of the dome is layered like an onion - layer of rock walls, then layer of empty space and so on. Layers are one tile thick and connections between them are far apart. Rock layers contain lots of irregularly placed transparent rock, so the end effect on LoS is like a broken mirror or crystal, it’s all weird. Of course Cacodemons that are placed more towards the centre of the “onion” will notice you and dig stuff up, so it’ll all turn very messy. At the centre of the “onion half” is a door to the second half of the dome.
The second half is a large room that holds a large green crystal (just crystal walls in a shape) and a couple of pools of water. Looks like a temple of sorts. Contains a boss group.
Boss ver. 1 (theme: demonic squatters): Named demonspawn (Amaemon Sr. perhaps? like Pargi/Parghit) and two spectral krakens. Boss has OTR and irradiate bolt (Irradiate, but bolt), or Irradiate Storm (scary stuff), boss is surrounded by halo (3-4 tile aura), that slowly gives contamination.
Boss ver. 2 (theme: living crystal defends itself from demonic squatters): Several green coloured Crystal Guardians that have poison/acid/physical energy bolts. Contamination aura like ver. 1. Can do little empty spaces in the large crystal to indicate where they’ve spawned.
Tiles: Overgrown stone, decaying forest, sickly green glass and crystal. The Glow of Crawl. Everything is irradiated.
Flavour: Olgreb was a reclusive and secretive wizard, jealously holding on to an extremely potent power source even as it eroded mage’s physique and sanity. After the wizard was gone, protective seals they put on the place weakened and a host of demons attracted by the power of the Crystal took lodgings inside the Dome. Also Olgreb was an octopode perhaps, hence the krakens :).
You enter the outskirts of the Olgreb’s Sanctum, the water here is rancid and the air is putrid. Everything is glowing.