Syllable/Rune-based magic system?
While I've never played it, Dungeon Master has a spellcasting system which sounds interesting. Basically, you form spells by sequencing various syllables: for example, by combining the syllables for "air" and "poison", you get a "poison cloud" spell. The syllables are categorised by elemental type, form, power etc.
I find this system neat because it makes spellcasting more like actually conjuring magical effects, and allows some experimentation to find out new spells, and experimentation is always fun.
The various elemental attack spells in ADOM would be easy to translate to a system like this, because they have so many overlapping elements. There'd be elemental type ("acid", "fire", "ice" and "lightning") and form ("bolt" and "ball/explosion"). The various utility spells, such as invisibility, identify and strength of Atlas would be tougher to do, because they're all very specific and have little overlap. But for starters, there are spells that deal with revealing information (identify, magic map, know alignment...) and curing (the various cure X wounds spells, neutralise poison, cure disease...) Some spells are basically opposites of each other, so including an "opposite effect" syllable sounds reasonable.
One downside is that the more syllables you have, the more combinations there are, making things difficult to design. And maybe spellcasting through sequencing syllables would be too tedious anyway.
You hit Andor Drakon, the ElDeR cHaOs GoD, and severely wound him.
The greater balor summons some help!
The ratling duelist disarms you. You drop your blessed Trident of the Red Rooster (+36, 6d12+18) [+12, +12]. It flies to the west.
Andor Drakon, the ElDeR cHaOs GoD, picks up the blessed Trident of the Red Rooster (+36, 6d12+18) [+12, +12].
Andor Drakon, the ElDeR cHaOs GoD, wields the blessed Trident of the Red Rooster (+36, 6d12+18) [+12, +12].