Magic bookshelf dungeon feature, which is heavily inspired by and is functionally similar to the TNNT swap chest, but only involves spellbooks instead of all items (and is not itself an object).

Looting while standing on it gives you a feeling you should put a book on the empty shelf, and if you do, you magically find other books on the shelf. You can see the identities of these books but do not permanently learn them if you didn’t previously know them. Once you take a book from the shelf, it vanishes.

Left up to the implementor whether the books would actually come from other players like the TNNT swap chest does (in which case it might end up filled with low-value or common books; if so, there are various ways this could be mitigated such as the shelf not accepting a book type it already has, or adding in randomly generated books) or whether the books would just be a pool of random ones selected at the start of the game.

An additional possible detail is that you can only see books on the shelf of equal or lower level than the total level of books you yourself have put in. So if you put in a level 1 book, you will only see other level 1 books, but if you then add a level 3 book, you will see books of up to level 4. Or, you always see all books, but only books below this threshold show you the spell and others appear as “a spellbook”. identities

Loadstones operate more subtly: they increase their weight every time you pick up a new item (one that you haven’t touched yet in the game). At some weight threshold, it autocurses and becomes undroppable.

Pet cats lose 2 tameness when the player wakes them up. However, opening a tin wakes all nearby felines, and this will not cause cats to lose tameness when woken.

A shop type which is one of those magical shops that you only see once and isn’t there when you go back, in which you can buy only one item. One possible implementation is that after buying an item, you are teleported out of the shop or even levelported to a nearby level, and then the shopkeeper and the rest of the items in the shop are removed, as well as possibly the entire room. There may be some need to prevent normal methods of theft from the shop. Alternatively, you could be permitted to buy multiple items, but the shop disappears after you leave.

If the player attacks a monster in melee immediately following a teleport (possibly only a spontaneous teleport), they get a backstab bonus on it, even if they’re not a Rogue.

Occasionally when a monster decides to use a teleportation wand as a defensive item, and the level is not non-teleport, it decides to zap you instead of itself.

Confused genocide doesn’t necessarily genocide your own species; it chooses a random genocidable species (which might be your own) and genocides that. If blessed, it picks a random monster class containing at least one genocidable monster (including @) and genocides that.

Another option is that confused genocide automatically picks a monster you have probably been thinking about, such as the nearest monster you can see (if you can’t see any other monsters, you can still see yourself!) or the last monster you saw or killed.

If teleportation fails because there is a trap or monster on the destination square, and there is an adjacent free square, you get placed on that square, possibly with a message explaining why you didn’t end up exactly where you wanted.

When you attempt to teleport to a square containing a monster, you exchange places with it rather than having the teleport fail and send you somewhere random. This possibly fails based on a monster magic resistance check.

If you are not fully healed by a potion of full healing, it prints some other message than “You feel completely healed”, like “You feel vastly better” or “You feel much, much better.”

Assuming bhaak’s bag of tricks proposal is implemented, allowing an empty bag of tricks to function as a sack:

When the bag is recharged, don’t destroy the contents. Instead, just make the contents inaccessible until it becomes empty again. Also, add a possible random effect to using the bag while charged: it spits out one of its contents at random.

Another proposal is to place the items in the bag into the inventories of the monsters created by the bag. It could even influence which monsters get created (e.g. a monster who will receive an orcish helm from the bag is likely to be an orc).

Negative “paranoia” intrinsic that randomly adds and removes fake invisible monsters on the map.

When an imp says “Look! Thy bootlace is undone!”, he might tie your shoes together and cause you to fumble for d10 turns.

You can consolidate wands of the same type by rubbing them on each other. This transfers one less than the number of charges in the wand (or just 1 charge if the wand has only one charge), and increments the recharge counter of the new wand. Overcharging a wand like this beyond its normal generation limits is likely to make it explode.

Hallucination should prevent against all death magic, including death rays, using the “near death experience” logic. Not just the touch of death.

High level (maybe only XL 30) monks can get enlightenment by sitting on normal floor.