Burnt offerings: via some mechanism, you get the corpse smoldering on the altar. When sacrificed, it is treated as higher difficulty.

Lithivorous monsters can gain intrinsic speed by eating a dilithium crystal.

Using a stethoscope on a monster requires that you succeed in making a to-hit roll against it. Otherwise, it doesn’t work.

Healers heal monsters when meleeing with no wielded weapon or worn gloves, sort of like nurses.

You can wield artifacts in your offhand, but they must be non-intelligent, non-gifted, and non-crossaligned. (Non-wished-for is an option, but may be too exclusive.)

Writing “Elbereth” in the prompt for writing a scroll should alias to “scare monster”.