Cavemen should be able to make cave paintings on the ground with blood (possibly their own blood, dealing damage to them, if they have a sharp object with which to draw blood). The available paintings are selectable from a menu, and each type grants a unique buff to Cavemen who stand on it, sort of like wards in dNetHack except not necessarily focused on warding off monsters. You learn more powerful paintings as you level up.

Procedurally generate the game-equivalent of Elbereth each game (the literal string “Elbereth” does nothing special anymore), and make it fairly likely to appear somewhere in the Dungeons of Doom.

When a spellbook’s ward is studied, it is possible to get a non-failure, non-success result of “you’re not skilled enough to tell if there is a useful ward here”. This is done by throwing the player’s Int, XL, and possibly other stats into some deterministic function along with the book’s object id and the ward it actually contains.