If you enter a room containing open pits of lava, print a message “It is hot in here.” If hallucinating, follow this up with “…but it’s a dry heat!”

A monster (imagined exclusively as a pet) that acts like your shadow in lit places, always being right next to you and possibly dying if it can’t be next to you, but if you’re in a dark area it is free to wander off.

Elves can read the runes on any elvish weapons (and probably also the runed wand). This doesn’t have to say anything important, it could just describe the item.

Nazgul can innately see invisible.