Using a cursed scroll of light to create darkness has some immediate effect that improves stealth in some way.

Gremlins generated not via cloning an existing one may spawn with a cursed scroll of light, and read it to create darkness when in the presence of brilliant light (Sunsword or gold dragon armor) or just randomly in lit areas when they sense an approaching player.

The scroll of light gives the player a light radius of 3 for a temporary amount of time, rather than lighting up a fixed area.

A blessed scroll of light lights up the entire level.

Izchak sells scrolls and wands of light, maybe spellbooks too, at low frequencies.