Restructure Gehennom to be very short, containing the Valley, the three Wizard’s Tower floors, and a “nexus” floor at the bottom, containing the vibrating square and four magic portals, each leading to a randomly selected demon lair.

You can only enter each lair once: you must decide whether to attempt defeating the demon lord or not before leaving. The exit portal won’t work if invocation items are left behind. The demon lords are beefed up from vanilla, and are not bribeable since they’re not guarding access to the stairs to extort passage.

As incentive for defeating the demon lords, they apply debuffs on the ascension run, described in #3396.

Portal stones: gray stones which are only useful in pairs (and which only 2 may generate in the whole game). They are used by putting one stone at a location you want to return to later, then later on activating the other one by rubbing it on your hand or something, which opens a temporary magic portal to (or levelports you to) the first stone.

When monsters levelport, they leave behind a magic portal which lasts one or a few turns, which you can use to follow them, to emulate how monsters can follow you when you levelport.

Add a system for casting ritual spells: more powerful and more expensive spells which have some esoteric effects you can’t get otherwise. The main differences between ritual and normal spellcasting are that they consume valuable, hopefully non-renewable components, take a number of turns to cast instead of taking effect instantly, and may require you to be in or set up certain circumstances.

Various ritual spells that have been proposed:

• Ball spells which consume a gem as focus and create a ball of elemental power that hits surrounding squares but not you. (Long casting times would probably make rituals infeasible for combat though.)
• Temporarily increase your carry cap by a great amount. (Other new intrinsics as required.)
• Resurrect a corpse as a tame monster (necromancy).
• Grant temporary intrinsic life saving.
• Single controlled polymorph with a greatly increased duration.
• Summon a demon, demon lord, or demon prince. Requires 5 cursed candles and a marker (to draw the classic pentagram). If summoning a named demon lord, it’s either random or there’s some expensive way to control who shows up. The demon lord could be peaceful, but with current behavior this is useless. Possibly summoning them allows you to make a pact with them.
• Remove the graveyard status from a level (would need to be expensive, and perhaps involve the Book of the Dead, and multiple different headstones).
• Grow a tree. This consumes at least a piece of fruit. For anti-farming the tree should probably not produce fruit or bees when kicked.
• Create a portal between two levels of your choice (doesn’t work with the Amulet obviously, but otherwise works)
• Create an artifact (that is, you somehow imbue an item with properties it can’t normally get).
• Bless items. Consumes a blessed scroll of remove curse.
• Genocide a genocidable monster. Consumes a figurine of that monster plus other costly things.
• Reverse genocide a monster. The monster may or may not have to be normally reverse-genocidable. Consumes a figurine of that monster plus other moderately expensive things.
• Charge something. Requires a rare ingredient - perhaps a dilithium crystal.
• Summon tame elemental(s). Among other things, ingredients include: a potion of water, any beatitude (water); a rock (earth); lit candles, a lit oil lamp, or a lit potion of oil (fire); an amulet of magical breathing (air).
• Create a magic lamp. Needs an oil lamp (of course) and a figurine or mask of a djinni (or possibly a nearby live djinni).
• Make the current level non-teleport. Requires a scroll of teleportation and that the caster be standing on an anti-magic field at (?) either the start or the end of the ritual.
• Create a fountain. Requires a statue of a medium-sized or larger monster, which gets destroyed (by turning it into the centerpiece of the fountain). There may be potential for wishing abuse; perhaps the fountain should be flagged so that it can’t produce a wish-granting water demon.
• Turn a regular knife into an athame. Components include other bladed weapons with positive enchantments adding up to 20 or something; all of these charges will be drained to +0 in the creation of the athame. The resulting athame is +0, regardless of the charges on the component weapons or original knife.
• Create a tame golem or golems. Requires a large amount of total weight of objects made out of the golem’s material.
• Summon a coaligned angel or other minion of your deity as a pet.
• Create a tame wood nymph from a tree (only once per tree).

Ritual spells come in spellbooks like usual, but aren’t stored in your spell list. Instead, reading the spellbook prompts you if you want to begin its ritual and tells you the necessary ingredients and circumstances you need to satisfy as preconditions. If you meet all the conditions and answer yes, you initiate the ritual. (For simplicity, this should probably burn up / expend all the components instantly.) You cannot begin a ritual while in the process of casting another ritual; this should probably be implemented as a precondition.

Apart from the component cost, rituals act as a constant drain on your Pw until the ritual is complete. If something distracts you in the middle of the ritual, you can go take care of it and then resume the ritual as long as you have the Pw left to finish it. (You could also drink gain energy during the ritual.) The only way for a ritual to fail, possibly backfiring with bad effects, is for you to run out of Pw while it is incomplete.

In addition to its preconditions, each ritual also has some postconditions: common to all rituals is that you have been casting the ritual for at least some length of time, but there may be others, such as standing on the square where you began the ritual, or have another item, or kill a monster, or something. There may also be other conditions such as “moving off the space where the ritual started breaks and halts the ritual”.

Every time you stop casting a ritual (whether it succeeded or failed), it increments the spellbook’s spestudied field; the book will eventually disintegrate after casting it a certain number of times.

The player is able to do some sort of ritual that involves sacrificing 25,000 gold pieces to open a portal to Fort Ludios if one has not already been generated. Possibly this would have to be done in a vault. If a naturally generated portal does already exist, the gold is still expended but the attempt to make another one fails.

The magic portal to the Ice Queen’s Realm should always be placed in a closet. Optionally, the closet could contain a cloak and the level could contain other references to The Lion, The Witch and the Wardrobe.

Allow the player to teleport directly onto a magic portal.

The travel command should select a magic portal, if one exists, before any other trap when the user is at the prompt to pick a destination and presses ^.

If you try to go up or down stairs or enter a magic portal, and there is a pet that is still eating next to you, you are prompted to confirm changing levels. Also remove the “foo is still eating” message since it will then be covered in the prompt.

Magic portals are never hidden.

Whenever you arrive on a level through a portal, either the portal moves a short distance or you appear a few spaces away from it. Or turn all 2-way portals into paired 1-way portals which can have different arrival coordinates defined.

A magic trap that causes you to yearn for your distant homeland may instantly magic portal you to your quest home level (perhaps asking you first).

The portal on the Plane of Fire moves around, one space in a random direction each turn. Never onto lava or another trap.

Portals on the Planes generate non-hidden, so you don’t need to bring mapping items for them.

Fort Ludios is a visit-once level: once you leave by the exit portal, the Dungeons of Doom portal disappears and the level becomes inaccessible forever. (Maybe if you leave any of the invocation items or the Amulet there, the portal refuses to let you out so the game doesn’t become unwinnable.)

Make all magic portals on the Elemental Planes immediately visible. The challenge should be surviving for long enough to get to the portal, not wandering around till you find it. This is because “Hunt for the Magic Tile” already exists on the vibrating square level, and is not very compelling.