5e Death Save Alternatives: Two Different Ones

Type I: Brutal Wounds 

When you get knocked down to 0 hp (assuming lethal intent), you are wounded, and have a chance of dying. Roll 1d20 to see how bad it is:

20: But a scratch. Oh, I guess you weren't hurt after all. You're at 1 hp.

15-19: Flesh wound. Disadvantage on ability checks until short rest.

10-14: Serious wound. You fall prone until someone helps you up. Disadvantage on attacks, checks, and saves, Speed is reduced by half. If you have access to spells such as cure wounds, the wound can be healed over a long rest. If you don't, it could take months.

5-9: Death's door. Unconscious. Make another save on your next turn:

20: you wake up with 0 hp and a serious wound

15-19: stable; wake up in 1d4 hours with 0 hp and a serious wound

5-14: still at death's door; try again next round

1-4: death

Any further attacks while at death's door are lethal.

2-4: Death (heroic/tragic/dramatic).

1: Death (comedic/embarrassing).

If you're lucky enough to survive at 0 hp, any further damage you take will call for more death saves. Roll with disadvantage, and ignore any result that's not worse than your current situation.

All glory to The One Death and Dismemberment Table to Rule Them All, but it was a bit too complicated for my tastes (and potentially too graphic for general audiences). My version is simpler and more handwavy, though it shares some of the inherent problems (like interactions with healing mechanics, which will have an impact on the structure of the campaign).

Type II: Creeping Death

When you are reduced to 0 hit points, you fall unconscious and are dying. Roll a death saving throw immediately, then at the start of each of your turns:

20: Two successes
10-19: Success
2-9: Failure
1: Two failures

Keep track of your successes and failures. When you get three failures, you die. When you get three successes, you stabilize. When you are restored to positive hit points, you stabilize.

When you stabilize, erase your successes and stop making death saves. You wake up after about an hour. Do not erase your failures until after you finish a long rest.

The goal with this system was to create a lingering consequence for falling to 0 hit points, but without crippling the character. In this system, your death save failures pile up over the course of the adventuring day. So, each time you fall to 0, you have a chance of sliding closer to death. 

In vanilla 4e and 5e, the dominant strategy for healers was to wait until someone got to 0, then heal them. I've heard it called "jack-in-the-box combat." He's down! He's up again! He's down again! He's up again! Not so in this system.

Gargantuan Crab, Steamed (CR 10)

This 40-foot crab is bright red and smells delicious.

gargantuan undead, neutral evil

AC 17 (chitinous carapace)

HP:

Body: 145 (10d20 + 60)

Right claw: 33 (2d20 + 12)

Left claw:  17 (1d20 + 6)

Speed 40 ft

Str 21 (+5), Dex 9 (-1), Con 22 (+6)

Int 10 (+0), Wis 7 (-2), Cha 1 (-5)

CR 10 (5,900 XP)

In lair: CR 12 (8,400 XP)

Immune fire

TRAITS

Meaty Claws. The crab's claws have separate hit points, and can be attacked separately from the body. If a claw dies is reduced to 0 hit points, that claw is killed. If the body is reduced to 0 hit points, the crab is killed.

Amphibious, Spider Climb, etc.

ACTIONS

Multiattack: The crab makes as many claw attacks as it has claws, then a bite attack against one creature in its claws.

Trample: The crab makes a leg attack against each creature in reach (maximum 8 targets).

Claw: +9 to hit, reach 10 ft, one target. Hit: 27 (4d10+5) bludgeoning damage. A Medium or smaller creature is grappled (escape DC 19). Each claw can only grapple one target at a time. Target is dropped if claw is killed. (Into the boiling water, if the crab is in its lair.)

Bite: +9 to hit, reach 0, one creature grappled by the crab. Hit: 21 (3d10+5) slashing damage.

Leg: +5 to hit, reach 5 ft, one creature. Hit: 16 (2d10+5) piercing damage.

The Crab's Lair

The crab lives in a naturally boiling lake in the middle of the tundra, spanned by a narrow bridge. It mostly stays underwater, but springs out when prey are near.

ENVIRONMENT FEATURES

Steam. The steamy air rising from the lake is pleasantly warm compared to the icy tundra for miles in every direction.

Boiling water. Any creature submerged in the lake takes 14 (4d6) fire damage at the start of each of its turns.

Bridge. The bridge has no convenient means of climbing back up if you've fallen off. Better lower a rope or something.

LAIR ACTIONS 

The crab magically causes one of the following effects each round at Initiative 20. It can't use the same one twice in a row.

Wave of water. A wave of boiling water strikes a 10-foot length of the bridge. Each creature in the area must make a DC 13 Strength saving throw. Success: 3 (1d6) fire damage. Failure: fall into the boiling lake.

Water level rises. Boiling water rises knee-high for the rest of the round. Everyone take 7 (2d6) damage at the end of your next turn if you're standing on the bridge.

Inspired by a misreading of a classic module, this bastard has become a legend in our game group. To bring him back for 5e, I've beefed up the stat block to play more like a real boss fight, not just a sack of hit points with basic attacks.