1. Bring back level draining.
2. Players will then be fearful of having their levels drained, PLUS you can keep knocking them back to 1 and they can be afraid of that, too.
3. ????
4. Profit!
Oh, god. Level drain. Plsno.
However, in my campaigns, I've never felt that at any point my players have felt safe; in fact, my players know that I play everything straight, and prepare the world as it would make sense. This means that, if they're level 5 in a dungeon and it makes narrative sense for there to be a full lich there, well, there's an
actual lich there. My players expect and respect my writing ability to make sure they're aware of the fact that they might be getting in over their heads before they do so.
That's a narrative, DM-side viewpoint, of course! I help that along by having a few special houserules.
1. HP does not reset on a long rest. Instead, during a long rest, you get to spend hit dice, just as if you took a short rest; at the end of your long rest, you get back half the
remaining hit dice you have, minimum 1. Things like bard's Song of Rest works on a long rest, as well as a short rest.
2. Failed death saves do not reset until a character takes a long rest. This means that, if a character drops and has to make a death save and fails, that failure doesn't go away if the cleric/bard/druid/whatever brings them back to functionality. Successes, of course, go away when a character is back above 0 hit points, because it wouldn't make sense otherwise. I considered imposing exhaustion levels instead of having failures on death saves not reset, but ultimately rejected it as being a little more difficult to keep track of.
3. Lingering Injuries. I know people sometimes don't like these, but I find it adds a certain amount of danger to every single combat, regardless of level. I do, however, slightly modify when lingering injuries come up, as follows:
* When a creature takes a critical hit, the attacking creature rolls 1d20; on an 11-20, the target takes a lingering injury.
* When a creature drops to 0 hit points but isn't killed outright, the attacking creature rolls 1d20; on an 11-20, the target takes a lingering injury.
* When a creature rolls a natural 1 on a saving throw against a trap or magical effect, the DM rolls 1d20; on an 11-20, the triggering creature or creatures take a lingering injury.
* When a creature fails a death saving throw by 5 or more, or automatically fails a death saving throw for any reason, they take a lingering injury.
The important part, however, is that every houserule above also applies to NPCs and monsters (where it makes sense, of course; an ooze doesn't have limbs to amputate, after all). There have been two combats where the characters were in a rough spot, but a lucky lingering injury changed the dynamic of the fight
completely, and made for a very dramatic reversal of fortune. I keep meaning to make my own DM screen that includes this stuff, but never seem to get around to it...
Changing character hit points per level, wholesale rewrites of the game's mechanics, etc, feels unnecessary! I don't want to do all that work; I already have too many projects to work on as it is.