A variant cursed effect of a scroll of genocide: it removes most monsters of a given species, but sends the survivors to you looking for revenge.

Using genocide breaks pacifist conduct.

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.

You can genocide the Wizard of Yendor (possibly only once, in his initial incarnation). This will leave the Book dropped in his tower, but since this counts as killing him, harassment begins immediately. When he returns after being genocided, he says “So… thou thought thou couldst genocide me, fool.”

New artifact Pandora’s Box, a large box that, whenever it is opened, ungenocides all genocided monsters and spawns one of each genocided species somewhere on the level.

You can’t dip successfully for Excalibur if water nymphs are genocided (and maybe extinct, as well). Not because you killed the Lady of the Lake, but because she’s mad at you.

Make djinn genocidable. If djinn have been genocided, they will not come out of smoky potions, so this can be used to ensure that your smoky potions of full healing will work properly.

“while already on Charon’s boat” is appended to the death message whenever the game ends with the player’s own role genocided, not just when they quit. Possibly it’s left off if the player ascends.

Confused genocide (uncursed or blessed) does not genocide you. Instead, it sets a level flag that prevents any more monsters from spawning on that level via the normal mechanism for the remainder of the game. (Monsters already created are unaffected.)

Genocides can only be targeted on monsters you can currently see. This means if you want to blessed-genocide L, you actually have to go and find a lich and read it in its presence.

Track monsters that you have named. If you genocide a class of monsters that contains any you have named, notify the player of their death.

Entering ‘*’ at the prompt for genocide does a current-dungeon-level genocide attempt of all creatures. Cursed reverse genocides random monsters, blessed kills all monsters level-wide subject to a resistance roll, and uncursed does the same but in a smaller radius.

If you ascend while polymorphed and your role is genocided, your god gives you some YAFM.

Alternatively (or additionally), the game is recorded as “ascended while on Charon’s boat”.

Genociding part of an amalgamation turns the monster into a non-amalgamation of whatever its other half is.

Replace blessed genocide’s class genocide effect with one that lets you name multiple species not from the same class.

You have a lower chance of genociding monsters, wishing for items, and identifying canned food if you have never seen the monster or item in question.

Remove the scroll of genocide, or else institute some awful (divine?) punishment for genociding monsters, because it is a heinous act. (This would help with symmetry for monsters using genocide.)

There should be one major monster of each alignment that is ungenocideable: Archon for lawful, deep ettin for neutral, arch-lich for chaotic.