Spell of elemental fist: after casting it, your next barehanded melee attack that connects causes an elemental explosion centered on the target. This could take over as the special spell for Monks.

Not specified how the element gets chosen, whether there should be multiple different spells each of a different elemental fist type, or whether it should use an alternate set of elements (stones/waters/metals/winds/fire like the Monk rank progression) versus basic NetHack elements like fire, cold, and shock.

Consider adding role spell lists like in D&D, in which your role dictates which specific spells you can learn. If you would successfully read a spellbook whose spell isn’t on your role’s list, you get told “[Your role] isn’t allowed to learn this spell”, similar to the message for twoweaponing. This could be extended to races and alignments, but extending it to genders would probably be too silly.

A simple initial way to do this would be to make each role’s special spell exclusive to that role.

Give all roles permanent knowledge of their role’s special spell starting right at the beginning of the game. The expectation is that a starting character probably can’t cast it, but will be able to given time.

Once you have learned your role’s special spell, you never forget it.

When you are gifted a spellbook by your god as a prayer boon, the book will always be your role’s special spell if you don’t already know it. (Possibly, they won’t give it to you if you have it identified, or they will give it to you if you know but have forgotten the spell.)

Change the Rogue’s special spell to knock rather than detect treasure.

In variants that have the Pirate role, this would free up the spell of detect treasure to be their special spell.