Getting amnesia can strip your knowledge of (and therefore ability to write) Elbereth.

Remove the Elbereth from the floor in Sokoban, since this means that anyone who finishes Sokoban automatically gains knowledge of Elbereth. Instead, place a burnt Elbereth somewhere random on the 9th to 14th levels of the dungeon.

Elbereth only protects you when the game considers you a beginner.

Aggravate monster, as well as possibly wielding Stormbringer, disables Elbereth’s protection.

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.

If you attack a monster while standing on Elbereth, all monsters in line of sight stop respecting Elbereth.

Conflict negates Elbereth protections.

Having an Elbereth square fade under you in 3.6.1+ makes the square permanently unengravable.

You should be prompted to confirm before attacking a monster while standing on Elbereth.

Elves can engrave Elbereth and use it on the player, scaring them.

Make Elbereth work the same as it did in 3.4.3 for animals or mindless creatures, but intelligent foes won’t be scared by it, they merely won’t attack in melee.

Elbereth should work from the very outset of the game, but get less effective over time.

Elbereth should not work until the hero discovers it in-game. (Similar to dNetHack’s wards.)

The list of monsters that ignore Elbereth should be increased, but the list of monsters that ignore scare monster should remain the same or decrease (3.6.0 Quest nemeses excepted). Perhaps scare monster should be renamed to “scare creature”, as it scares humans and elves, which are not really monsters.