At a guess, something to do with the fact that 'N' and 'x' are not monster types?

x is unmaker and they can be numerous. you might die if low on hp so a confirm is nice

'n' is the repeat key for the regular keyset, and 'X' is the repeat key for the roguelike keyset.

Staves of genocide in particular have very high fail rates for most characters, so it's not unusual to see 100 consecutive failures before the staff is successfully used on attempt #101. By that point, most players will already be sitting on (or prepared to hit) the repeat key to initiate attempt #102...

Bug: Trap Doors, Disarming, Levitation, and easy_disarm
 

With levitation and with easy_disarm off, walking into a trap door ignores it, and failing to disarm a trap door ignores it. Expected.

With levitation and with easy disarm on, walking into a trap door ignores it, and failing to disarm a trap door procs it.

EDIT: rhukath's the one who pointed out the bug, I just did a bit of poking and the report.

Bug/RFE: Beaming spells destroying loot underfoot
 

Spells that beam will destroy loot you're standing on top of—even though the animation doesn't look like it hits the square you're on at all. Requesting this be changed to not happen.

Bugs/Crash: Mimics and Banor=Rupert
 

Mimics mimicking Banor=Rupert, using his Something Weird, immediately cause a game crash. I have a feeling there are similar instances for other monsters and possibly powers, but I don't conclusively know what those might be.

Tangentially for Mimics, spell cost and effect power for various monster spells aren't displayed for the player.

EDIT: Bug courtesy of bostock.

Skill notifications on level up
 

Is there a way/option to be notified when learning new spells and powers on level up?

For spells, not strictly, but you can check ~s, ~x, or browse books to see what levels spells are, and use that in conjunction with spell studies (which if available are diplayed on the main screen in the sidebar) to know when you learn a new spell (but only for books you already have or have learned from, I think).

For powers, there's an option to spoil future powers that aren't yet available to you in the powers menu.

Thank you. I thought it was a bug with my config at first. This ~ menu slaps, quite too bad it doesn't highlight recent changes (~x info as a Death Sword for example) but it's very useful

Bug: Reading ?ArtifactCreation and Keeping It (on a non-Scrollmaster)
 

[11:49] Incitatus: if you read ?art creation, and close the game window before you name it, you keep the artifact and the scroll
[11:49] LucyFurr: Awesome exploit.
[11:49] MITZE: What's the art named though
[11:50] MITZE: if you do that
[11:50] Incitatus: it's an artifact but it has no name, and doesn't "count" against artifacts created, or even ?art creation read