Take a Downside to Solve the Accomplishing Nothing Problem

The Accomplishing Nothing Problem:

• If you are in combat and get hit by an effect that temporarily takes you out of the fight and you fail your save, you are about to spend an amount of real-world time potentially measured in hours doing nothing. That's a recipe for player disengagement at best.
• If you cast a high-level spell and your target makes their save, not only have you wasted your Action, you have blown one of your main limited daily resource, and accomplished nothing to show for it.

The Swedish TTRPG Dragonbane has a solution where, if you fail a roll, you can take a bane to one of your abilities to reroll.

I've been rolling around in the back of my mind, and trying to remember, the possibility of offering a choice of minor consequence to turn an almost-success into a success.

Then, recently, I had a burst of inspiration in the shower, and hacked together some actual numbers and stuff. The main downside is it may be too complicated, though I laid it out in a way that flows fairly well, at least for my mind.

To wit:

On Bringing Back Ability Damage

In D&D 3.5e, we had Ability Damage. Things (especially poison, but also other stuff, especially various creatures) could deal damage directly to an ability score -- if you take 1d6 Strength Damage, your Strength score goes down by 1d6 (so your Strength modifier correspondingly goes down by about half of 1d6).

If any of your Abilities reach 0 from damage, you are, depending on the Ability, paralyzed (a physical score), unconscious (a mental score), or dead (Constitution). If you take an 8-hour sleep, you heal damage in each damaged Ability by 1; if you take a 24-hour sleep, you heal each by 2. You can also take Ability Drain, which is basically the same but it doesn't heal without magic.

The designers of 5th Edition, of course, judged this all absurdly fiddly and mathy -- not only do you have to track each of your current Ability scores separate from your actual Ability scores (plus keep track of how much is Damage and how much is Drain), you also have to do the (x-10)/2 (rounded down) thing for each one to calculate your current and actual Ability modifiers -- and, probably rightly and correctly, dispensed with the whole thing.

I do find its loss very mildly unfortunate. It did allow a fair bit of differentiation between monsters. This guy just paralyzes you, that guy gradually makes you more sluggish until you're paralyzed, the other guy makes you dumber until you're paralyzed, and so on.

To the rescue: the OSR stylings of Swedish TTRPG Dragonbane!

In Dragonbane, each Ability score can have or not have a Condition. If you have a Condition in an Ability score, every time you roll that Ability for anything, you simply roll with what in 5e would be called Disadvantage (in Dragonbane, it's called a "Bane").

Porting that back to 5e, we could, while maintaining a high level of simplicity, have 3 (or even 4) levels of "ability score damage":

• Regular, undamaged (roll normally)
  If you then fail a save vs Ability Damage:
• Damaged (all rolls with that Ability have disadvantage)
  If you then fail another save vs Ability Damage in an already-damaged Ability:
• Paralyzed/Unconscious (or, if Constitution, unconscious and making Death saves)
  We could also introduce some sort of blessing/boon/etc that goes the other direction:
  
• Blessed or something (all rolls with that Ability have advantage, with the side benefit that you have an extra level of buffer against Ability Damage to that Ability -- failing a save vs Ability Damage when you're blessed in that Ability just brings you down to normal)

We could take Dragonbane's names for the Conditions (Exhausted, Sickly, Dazed, Angry, Scared, and Disheartened), some of which are already used in 5e (plus the term "Condition" itself has a 5e meaning, too). We could just call them Bane and Boon to Abilities, terms which are mostly not already in use.

Ettin Newcanon

Ettins, ubues, and other giants with extra heads or limbs, are all results of a semi-rare disorder in trolls, sometimes arising spontaneously, sometimes resulting from slashing blows that land in just the right place, where an extra head and/or one or more extra limbs are "re"generated. Such creatures generally lack the natural keen regenerative abilities of trolls, as their natural regeneration is too busy keeping them alive as these abominations to keep up with incoming damage as effectively.

BY CROM

So the Iron Heart Surge maneuver (Tome of Battle) has many known problems. Among them:

• It doesn't limit what Conditions it can end, leading to preposterousness like ending the Dead condition, or only-slightly-less-preposterous ending Ability Damage or Drain.
• When it ends a spell or effect, it ends it entirely, not just on the initiator. Drow uses IHS to BY CROM away the blinding effect of the sun? No more sun.
• It takes a standard action to initiate, meaning that most of the most devastating Conditions in the game (Stunned, Paralyzed, Nauseated, etc) are not susceptible to being IHSed away.

Any IHS fix needs to address at least the first two problems. The third is a misfortune (and perhaps unintended) but not outright dysfunctional, so an IHS fix doesn't need to address it, but it's nice if it does.

So here's my proposed fix:

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Iron Heart Surge

Iron Heart

Level: Warblade 3

Prerequisite: One Iron Heart maneuver

Initiation Action: 1 standard action

Range: Personal

Target: You

Duration: See text

By drawing on your mental strength and physical fortitude, you break free of a debilitating state that might otherwise defeat you.

Your fighting spirit, dedication, and training allow you to overcome almost anything to defeat your enemies. When you use this maneuver, select one of the following effects currently affecting you. That effect ends immediately.

• Blinded
• Confused
• Dazzled
• Deafened
• Entangled
• Shaken
• Sickened
• Ability or HP Bleed (does not restore lost ability score or hit points, but does stop further loss)
• Poisoned (does not remove the effects of poison you've already taken, but does prevent the poison's secondary effect)
• Any spell, power, spell-like ability, maneuver, or other effect with a listed duration other than Instantaneous

When you use this maneuver, the effect ends on you. It does not end at its source; other characters may still be affected.

While this maneuver can end most charms and compulsions, your character (depending on the exact nature of the effect) may not realize they are affected by such an effect, or may not be able to act against the will of the caster of the compulsion by initiating this maneuver.

When you initiate this maneuver, you also surge with confidence and vengeance against your enemies, gaining a +2 morale bonus on attack rolls until the end of your next turn.

If your initiator level is at least 10, you may initiate this maneuver on your turn even if a condition or effect currently renders you otherwise unable to take Standard actions. The effects you can end at this level include the above, and:

• Frightened, Cowering, or Panicked
• Dazed
• Fascinated
• Nauseated
• Paralyzed (unless paralyzed because of Ability Damage or Drain)
• Petrified
• Stunned
• Turned or Rebuked