In fantasy works like Lord of the Rings, the vertical dimension often helps the protagonists in gravity-enhanced combat (in other words, pushing foes off high walls or into chasms to kill them). I would like to incorporate such high places to push foes down from for my players to use in my upcoming D&D 5e campaign because I like both the imagery of tall towers and the tactics involved.
However, high places cut both ways — if there's a chasm deep enough to instantly kill a monster falling down it, it will also be equally dangerous to my players' characters using normal fall rules in the Player's Handbook. I could add a saving throw to grab the ledge, but I don't want high falls to become a save-or-die situation for my players. I don't want to make the threat of fighting in such places negligible either.
I'm looking for a way to handle very high fall hazards that keeps them dangerous but not too dangerous.
Currently I'm expecting that the solution will be either an official rule or a tested homebrew rule for really high falls that
- is useful to the players when applied against monsters
- can pose a serious threat to the player characters too, but is unlikely to be directly lethal unless the character has suffered moderate damage already (harmful is fine, single save vs. death is not)
- apart from character death, doesn't remove PCs from the combat encounter for extended periods (I think that'd be boring for the players involved)
- possibly asymmetric: I'm fine with monsters receiving worse treatment
Also note that the rule doesn't have to actually involve PCs falling when pushed off a ledge: "you stumble and grab the ledge, but the effort of keeping yourself from falling saps your endurance by 2d8 hit points" would be an appropriate, if boring, idea.