D&D 5E HP thresholds and control: a custom system

[Olrox17]

EDIT: I’m back after a year of playtesting the threshold system. I’m editing this post with all the changes, fixes and improvements made in the last year.

Check the following spoiler block if you wish to read a long explanation of why I embarked on this project. You can skip it.

Spoiler

There are two things that I really like about 5e that were missing from third and fourth edition: bounded accuracy (and bounded “numbers” in general) and the fact that magic items aren’t needed to keep up with the game’s math.
The lack of continuously inflating attack bonuses and defenses on the monster’s side removes the need for a “treadmill” of magic items. The constant need for larger plusses is finally gone, and I like that.

There is one problem though. Or at least, it’s a problem for me, but I’m pretty sure it’s a problem for a lot of other fifth edition players and DMs. And the problem is, saving throws & save DCs scaling, coupled with hard control spells and abilities.
I think we’re all familiar with the issue. Save DCs rise constantly, both on monsters stat blocks and on PCs character sheets, but saving throw bonuses to not climb at the same pace.

On the PCs side, the consequence is that at first level a typical PC will have 2 good saves it can pass with an 8 or so, another couple of decent saves where it gets a 50/50 shot, and one or two bad saves where a 13 or 14 is needed, but the higher level it gets the more things get weird.
At level 20, the PC will usually still have two good saves, and maybe also another decent one with the Resilient Focus feat, but all other saves will be terrible. Like, need to roll a 18, 19 or 20 kind of terrible.

On the monster side, things are more varied, but as a rule of thumb, if a monster doesn’t have legendary resistance IT WILL be hard controlled by your average PC party. There are far too many options: hold person, phantasmal force, suggestion, maximilian’s earthen grasp, fear, hypnotic pattern, stinking cloud, banishment, confusion, Evard’s black tentacles, otilukes’s resilient sphere, polymorph, watery sphere, etc.

My first idea to solve this issue was to give a scaling bonus to non-proficient saving throws to everyone, both monsters and PCs. Something like half proficiency, to keep to lowest saves from being auto-fails.
However, this is not enough IMO. Thing is, as you get to higher level in this game, control effects NOT ONLY get harder DCs, but they also get more common (read spammable) AND more powerful (very long durations with no save to end, large AoEs etc). Heck, forcecage and maze allow NO save.

Several spells in the game already use a form of HP threshold. Sleep, Color Spray, Power Words. If the target has more than a certain amount of HP, the spell is going to do less, or nothing at all.

What I did, in short, is extending the system to every spell and ability in the game that inflicts major control over the target.
But I don’t want to make it so it works like an immunity. Because casting hold person on the black knight just for the DM to say that he has too many Hit Points to be affected by the spell is, well, boring. It’s just a waste of a spell slot and it feels unfair.

How does it work then? Well, if the black knight fails the saving throw against hold person but does have more Hit Points than the spell’s HP threshold, he’s still going to suffer a negative effect. It’s just not going to be full-blown paralysis. Rather, his speed is halved for the same duration.

So that’s how it works. Hard control spells and abilities will only inflict a partial, lesser effect on a target with more current HP than the threshold. One important thing to note is that this system relies on a very specific notion of Hit Points, that are not just "meat" but also "a combination of physical and mental durability, the will to live, and luck" (cit. PHB).

The HP Threshold System

Control Spells

Every spell in the game that inflicts a debilitating condition is now defined a control spell.
Control spells will inflict a different effect than normal when their target’s CURRENT hp are above a certain threshold.

Increase the HP threshold of a spell if you’re casting it on a higher level spell slot.
For example, phantasmal force, a lvl 2 spell, normally has a 60 hp threshold. By casting it with a level 5 spell slot, phantasmal force now has a 100 hp threshold.

If the target’s current HPs drop below the threshold while the spell is still affecting it, the target looses the threshold’s protection and the spell reverts to its normal effects.
For example, hold person, cast with a level 2 spell slot, has a 60 HPs threshold. It won’t exercise its full effect on a fighter with 90 HPs. However, if the fighter takes damage and drops to 60 HPs while the spell is still active on it, the fighter is now paralyzed as per the normal effect of hold person.

There's a table for single target spells (such as phantasmal force, or hold person cast at its lowest level), and a table for multiple target spells (such as hypnotic pattern, or hold person cast at 3rd level or higher)

Single Target Spell HP Threshold

Spoiler

Level 1 slot: 40 hp
Level 2 slot: 60 hp
Level 3 slot: 80 hp
Level 4 slot: 100 hp
Level 5 slot: 120 hp
Level 6 slot: 140 hp
Level 7 slot: 160 hp
Level 8 slot: 180 hp
Level 9 slot: 200 hp

Multiple Target Spell HP Threshold

Spoiler

Level 1 slot: 30 hp
Level 2 slot: 45 hp
Level 3 slot: 60 hp
Level 4 slot: 75 hp
Level 5 slot: 90 hp
Level 6 slot: 105 hp
Level 7 slot: 120 hp
Level 8 slot: 135 hp
Level 9 slot: 150 hp

Logic behind the HP tables

Spoiler

The numbers were not picked randomly. A look at the DMG Monster Statistics by Challenge Rating should quickly reveal that each spell level is aimed to influence a certain defensive Challenge Rating. An example:

An AoE sixth level spell has a 105 HP threshold. A monster with defensive CR 3 has between 101 and 115 hp. So, under this design, a AoE sixth level spell is meant to exercise its full effects on a crowd of monsters with a defensive CR up to 3.

For comparison, a single target sixth level spell has a 140 HP threshold. A monster with defensive CR 5 has between 131 and 145 hp. So, under this design, a single target sixth level spell is meant to exercise its full effects on a monster with a defensive CR up to 5.

Here’s the list of every control spells currently in the game and how their effect is changed on a target whose current HPs are higher than the threshold.

Spell List
Level 1

Spoiler

Animal Friendship: no change
Bane: at the end of each of its turns, the target can make a Charisma saving throw. On a success, the spell ends on the target.
Cause Fear: the target has disadvantage on attack rolls instead of being frightened.
Charm Person: no change.
Compelled Duel: no change.
Entangle: Strength check action to break free succeeds automatically.
Ensnaring Strike: Strength check action to break free succeeds automatically.
Snare: Dexterity saving throw to end the effect has advantage.
Tasha’s Hideous Laughter: target is not incapacitated.
Wrathful Smite: Wisdom check action to break free succeeds automatically.

Level 2

Spoiler

Blindness/Deafness: spell lasts only 1 round on the target.
Crown of Madness: Wisdom saving throw to end the effect has advantage.
Earthbind: at the end of each of its turns, the target can make a Strength saving throw. On a success, the spell ends on the target.
Heat Metal: when taking damage, target does not get disadvantage to attack rolls and ability checks.
Hold Person: target is not paralyzed, but its speed is halved for the same duration.
Levitate: at the end of each of its turns, the target can make a Constitution saving throw. On a success, the spell ends on the target.
Maximilian’s Earthen Grasp: Strength check action to break free succeeds automatically.
Phantasmal Force: Investigation check action to break free succeeds automatically.
Ray of Enfeeblement: Constitution saving throw to end the effect has advantage.
Suggestion: at the end of each of its turns, the target can make a Wisdom saving throw. On a success, the spell ends on the target.
Web: Strength check action to break free succeeds automatically.

Level 3

Spoiler

Bestow Curse: at the end of each of its turns, the target can make a Wisdom saving throw. On a success, the spell ends on the target.
Blinding Smite: spell lasts only 1 round on the target.
Enemies Abound: at the end of each of its turns, the target can make a Intelligence saving throw. On a success, the spell ends on the target.
Fear: the target has disadvantage on attack rolls instead of being frightened.
Hypnotic Pattern: target is not incapacitated, its speed is not reduced to 0.
Slow: Wisdom saving throw to end the effect has advantage.
Stinking Cloud: target doesn’t have to waste its action, but it’s poisoned until the end of its current turn.

Level 4

Spoiler

Banishment: at the end of each of its turns, the target can make a Charisma saving throw. On a success, the spell ends on the target.
Charm Monster: no change.
Compulsion: Wisdom saving throw to end the effect has advantage.
Confusion: Wisdom saving throw to end the effect has advantage.
Dominate Beast: the target is just charmed, nothing else.
Evard’s Black Tentacles: Strength check action to break free succeeds automatically.
Otilukes’s Resilient Sphere: Dexterity saving throw to avoid the effect has advantage.
Phantasmal Killer: the target has disadvantage on attack rolls instead of being frightened.
Polymorph: unwilling target is restrained instead of transformed. At the end of each of its turns, the target can make a Wisdom saving throw. On a success, the spell ends on the target.
Sickening Radiance: target takes no exhaustion levels.
Watery Sphere: Strength saving throw to end the effect has advantage.

Level 5

Spoiler

Bigby’s Hand: target has advantage on Strength checks against the hand.
Dispel Evil and Good (dismissal): at the end of each of its turns, the target can make a Charisma saving throw. On a success, the spell ends on the target. After three failed saving throws, the target stays banished with no chance of coming back.
Dominate Person: the target is just charmed, nothing else.
Dream: Wisdom saving throw to avoid the effect has advantage.
Geas: no change.
Hold Monster: target is not paralyzed, but its speed is halved for the same duration.
Modify Memory: target is not incapacitated and is still aware of his surroundings; no memory changes.
Synaptic Static: Intelligence saving throw to end the effect has advantage.
Telekinesis: target has advantage on Strength checks against the caster.
Transmute Rock: target is not restrained, but its speed is halved for the same duration.
Wall of Force: target gets a Dexterity save, with advantage, to move up to its speed, as a reaction, before the wall forms.
Wall of Stone: Dexterity saving throw to move out has advantage.

Level 6

Spoiler

Bones of the Earth: Strength check action to break free succeeds automatically.
Eyebite: spell lasts only 1 round on the target.
Flesh to Stone: target is not restrained, but its speed is halved for the same duration. Effect doesn’t become permanent at the end of concentration.
Magic Jar: at the end of each of its turns, the target can make a Charisma saving throw. On a success, the spell ends on the target.
Mass Suggestion: at the end of each of its turns, the target can make a Wisdom saving throw. On a success, the spell ends on the target.
Otiluke’s Freezing Sphere: Strength check action to break free of ice succeeds automatically
Otto’s Irresistible Dance: target gets a Wisdom save to negate the spell entirely, Wisdom save action to break free succeeds automatically.
Sunbeam: target gets disadvantage on attacks rolls instead of being blinded.
Wall of Ice: target gets a Dexterity save, with advantage, to move up to its speed as a reaction before the wall forms, taking the 10d6 damage if passing through the forming wall’s space.

Level 7

Spoiler

Forcecage: target gets a Dexterity save, with advantage, to move up to its speed, as a reaction, before the cage forms.
Plane Shift: at the end of each of its turns, an unwilling target can make a Charisma saving throw. On a success, the spell ends on the target. After three failed saving throws, the target stays banished with no chance of coming back.
Prismatic Spray: Indigo color works like flesh to stone. If a target is banished to another plane by the violet color, at the end of each of its turns, the target can make a Charisma saving throw. On a success, the spell ends on the target. After three failed saving throws, the target stays banished with no chance of coming back.
Reverse Gravity: Dexterity saving throw to avoid the fall has advantage. At the end of each of its turns, a target can make a Constitution saving throw. On a success, the spell ends on the target.
Symbol: at the end of each of its turns, the target can make a saving throw (Constitution, Wisdom, Intelligence or Charisma, depending on the symbol used). On a success, the spell ends on the target.
Whirlwind: Strength check action to break free succeeds automatically.

Level 8

Spoiler

Antipathy/Sympathy: spell lasts only 1 round on the target.
Dominate Monster: the target is just charmed, nothing else.
Feeblemind: spell lasts only 1 round on the target.
Maze: target gets a Charisma save, with advantage, to negate the spell entirely.
Sunburst: blindness lasts only 1 round on the target.

Level 9

Spoiler

Prismatic Wall: initial blindness lasts 1 round rather than 1 minute. Indigo color works like flesh to stone. If a target is banished to another plane by the violet color, at the end of each of its turns, the target can make a Charisma saving throw. On a success, the spell ends on the target. After three failed saving throws, the target stays banished with no chance of coming back.
Weird: the target has disadvantage on attack rolls instead of being frightened.
True Polymorph: unwilling target is restrained instead of transformed for same duration. Effect doesn’t become permanent at the end of concentration.
Mass Polymorph: unwilling target is restrained instead of transformed. At the end of each of its turns, the target can make a Wisdom saving throw. On a success, the spell ends on the target.
Psychic Scream: Intelligence saving throw to end the effect has advantage.

Control Monster Abilities

HP thresholds applies to monster abilities as well. Every monster ability in the game that inflicts a debilitating condition is now defined a control ability.

Control abilities work just like control spells. The only difference is that monster abilities do not have spell levels, so they use different tables. These tables use the monster CR to determine HP thresholds.

HP INFLUENCED BY CR

Single Target Ability HP Threshold

Spoiler

CR 0 3 hp
CR 1/8 5 hp
CR 1/4 10 hp
CR 1/2 18 hp
CR 1 34 hp
CR 2 42 hp
CR 3 58 hp
CR 4 74 hp
CR 5 98 hp
CR 6 106 hp
CR 7 122 hp
CR 8 138 hp
CR 9 154 hp
CR 10 162 hp
CR 11 202 hp
CR 12 242 hp
CR 13 256 hp
CR 14 272 hp
CR 15 288 hp
CR 16 304 hp
CR 17 320 hp
CR 18 336 hp
CR 19 352 hp
CR 20 392 hp
CR 21 440 hp
CR 22 480 hp
CR 23 520 hp
CR 24 568 hp
CR 25 616 hp
CR 26 664 hp
CR 27 704 hp
CR 28 752 hp
CR 29 800 hp
CR 30 848 hp

Multiple Target Ability HP Threshold

Spoiler

CR 0 2 hp
CR 1/8 4 hp
CR 1/4 8 hp
CR 1/2 13 hp
CR 1 26 hp
CR 2 32 hp
CR 3 44 hp
CR 4 56 hp
CR 5 74 hp
CR 6 80 hp
CR 7 92 hp
CR 8 104 hp
CR 9 116 hp
CR 10 122 hp
CR 11 152 hp
CR 12 182 hp
CR 13 192 hp
CR 14 204 hp
CR 15 216 hp
CR 16 228 hp
CR 17 240 hp
CR 18 252 hp
CR 19 264 hp
CR 20 294 hp
CR 21 330 hp
CR 22 360 hp
CR 23 390 hp
CR 24 426 hp
CR 25 462 hp
CR 26 498 hp
CR 27 528 hp
CR 28 564 hp
CR 29 600 hp
CR 30 636 hp

It would be way too long and exhausting to provide a lessened effect for each monster ability in the game, so the specifics are left to the DM’s discretion. When in doubt, the DM can use the spell list as reference.
A ghost’s possession ability, for example, is similar enough to the magic jar spell that you can treat it the same way (at the end of each of its turns, the target can make a Charisma saving throw. On a success, the spell ends on the target).

Optional Rule: Spell Recovery
If the HP threshold system ends up feeling too harsh towards casters, consider implementing this rule: when you cast a control spell of 2nd level or higher, and the spell fails the impose any kind of effect on its targets, you regain one expended spell slot. The slot you regain must be of a level lower than the spell you cast. If the spell has no targets to begin with, you don’t regain a spell slot.

 

[Olrox17]

TL;DR: I'm building a system that applies HP thresholds to every form of hard control in the game. HP thresholds are already a thing in D&D 5e (sleep, power word stun, etc), and, since I like them, I want to use them every time there's a serious status condition involved.

 

[seebs]

This is a fascinating idea. I don't think I like it, because I think part of the point of save-based controls is to give you a way to have options against things with too many hit points. But it's an interesting idea, and I think you have correctly identified something of an issue with weak saves not scaling at all. But it's somewhat intentional that "target weak saves" is a tactic with actual utility.

 

[mellored]

You would need to change everyone's spell slots. As is, there isn't a lot a level 17 caster can do with a level 1 spell, except use it for control spells.

 

[Gadget]

Hmmm...the idea has some merit, Hit Points and damage are meant to scale more so than attack bonus and AC. However, I think some of the implementation is a little too draconian. Spell casters only get a very few high level slots after all. I can see the need for Force Cage, for example, not being an "I win" button for any opponent that fits in the cage, but I have hard time seeing how the incredibly weak Weird needs any more restraint, high DC or not. Prismatic Wall is a ninth level spell, let it have some bite; it already has a paltry ten minute duration.

Some of the others I would need to think about, but I like the idea of progressive effects with the likes of Hold Person in particular. The problem with that spell that it is such an all or nothing save or screw, that the devs felt they needed to give a save every round to mitigate the effect. All this is does is make it most likely to be saved against fairly quickly when the caster first acquires it, then making it nigh un-savable at high levels when the caster has a high DC. If the spell instead offered progressive saves such that on the first save the target was slowed, on the second, restrained, and the third paralyzed for the duration, it might make it more interesting. Then again it might just make it more convoluted than it is worth. Maybe the target only gets a Save (with advantage) when they take damage?

 

[Blue]

I agree with your basic premise. In some ways it's like AC, but unlike AC that has boosts for foes in terms of natural armor and such, saves are basically flat. Increased stats for foes still leave plenty of openings in terms of saves not advancing, and usually obvious ones (don't use STR or CON vs. an ogre, but maybe CHR or WIS would be good.)

The solution you are putting forth seems more to address the symptoms (reducing effects if a save is failed) than the root cause (too many saves stay low vs. (slowly) advancing DCs and fail a lot).

But, that being said, I love the idea of adding in an additional level of tactics where it's far from the best to throw out "nova" spells at the beginning of combat. You now get a balancing point - do I wait until later in combat, granting actions but having a bigger effect, or go now.

This even carries for straight damage spells. Fireball early, with the most targets (and the least intermingling of your front-liners), knowing that many/most/all of the foes will take reduced effect vs. waiting until more are under the threshold - BUT with focus fire you may end up with several targets dead and others still above the threshold.

Now, this does make fighter type PCs and foes more resistant to magic simply by virtue of having more HP. CON, already one of the three big saves, now serves double duty in helping to prop up against all failed saves.

This makes lower level slots drop off even quicker in offensive usefulness since not only will they have less effect vs. more powerful foes being lower level but will have a lower threshold so more likely that lesser effect will be even more reduced. I'm not saying this is a bad thing, but it is a balance changer when only a few highest level slots are available. Balance might be better suited by allowing spells of about 2/3 your max spell level are suitable against on-level opponents, allowing you to have a reasonable selection of slots that will affect your most common foes, and a few that will still work well when the encounters have fewer, more powerful foes.

It also seems to encourage throwing damaging spells first before debuffs in order to ensure that they are under the threshold. Mostly noticeable because it's not intuitive to the in-game narrative. "Burn them so that my prayer may bind them!"

It seems a straight-out weakening of non-support casters - at best they have by-the-book effects but they can also have them reduced. Do you see casters (of the various different tiers and types) as too powerful or should there be an offsetting bonus to them?

 

[Olrox17]

This is a fascinating idea. I don't think I like it, because I think part of the point of save-based controls is to give you a way to have options against things with too many hit points. But it's an interesting idea, and I think you have correctly identified something of an issue with weak saves not scaling at all. But it's somewhat intentional that "target weak saves" is a tactic with actual utility.

Good point. I agree that control spells are useful in breaking the routine of "I attack, I hit, I damage". And that's why I decided early on that HP thresholds should NOT grant an immunity, but rather a reduced effect.

An example:
A player casts hypnotic pattern (a third level AoE spell) on a Roc (CR 11, 248 HP). The Roc fails its save.
According to the rules, the Roc should now be charmed and incapacitated for quite a while, without a save to end the effect.
In my system, the Roc would now be charmed for the same duration. Not incapacitated. I'm pretty sure the players will still be able to use the charmed condition to their advantage!

You would need to change everyone's spell slots. As is, there isn't a lot a level 17 caster can do with a level 1 spell, except use it for control spells.

Yes, HP thresholds would definitely make control spells casted from low level slots less powerful. That's intentional. Right now, direct damage spells and control spell are roughly balanced at the time you get them. Fireball and Hypnotic Pattern, for instance, are both capable of wiping the floor with a group of, say, gnolls. The two spells are balanced when you both get them at level 5. Fast forward to high levels, when you're dealing with a group of frost giants. Fireball deals around 25% of their health, while Hypnotic Pattern is just as good as before, if not better, simply because you can now spam it. Crowd control spells get more and more overpowered as you level, because they stay just as effective while you get to cast more of them.

That said, it is my intention to keep control spells useful even when they have no chance to beat the HP threshold. Through a reduced effect, as I said above.

 

[Olrox17]

Hmmm...the idea has some merit, Hit Points and damage are meant to scale more so than attack bonus and AC. However, I think some of the implementation is a little too draconian. Spell casters only get a very few high level slots after all. I can see the need for Force Cage, for example, not being an "I win" button for any opponent that fits in the cage, but I have hard time seeing how the incredibly weak Weird needs any more restraint, high DC or not. Prismatic Wall is a ninth level spell, let it have some bite; it already has a paltry ten minute duration.

Some of the others I would need to think about, but I like the idea of progressive effects with the likes of Hold Person in particular. The problem with that spell that it is such an all or nothing save or screw, that the devs felt they needed to give a save every round to mitigate the effect. All this is does is make it most likely to be saved against fairly quickly when the caster first acquires it, then making it nigh un-savable at high levels when the caster has a high DC. If the spell instead offered progressive saves such that on the first save the target was slowed, on the second, restrained, and the third paralyzed for the duration, it might make it more interesting. Then again it might just make it more convoluted than it is worth. Maybe the target only gets a Save (with advantage) when they take damage?

You raise some very good points. None of the spell write ups are set in stone yet, it's still very much a work in progress, and you're offering some useful ideas! I may have been a bit too harsh on some of the spells, like poor old Weird

 

[Quickleaf]

I think the high-level control spells are meant to be taken in the context of a very different sort of game than many of us are used to playing. The defining feature of high-level is, I believe, a shift away from tactics toward longer-term strategy with moves and countermoves. Hard control high-level spells need to be viewed through that lens, rather than the lens of a single combat encounter.

Also, this would magnify a verisimilitude issue that I have with sleep:

A monster who you've hacked and stabbed and burned down to the appropriate HP threshold is suddenly...what...more susceptible to a sleep spell? What the Rust Monster!?! That makes no narrative sense...if anything an unsuspecting monster resting at ease or caught off-guard listening to a bard playing a tune should be more susceptible to a sleep spell in the narrative.

That similar incredulity applies to other hard control spells you mention like maze or whirlwind.

To work, narratively speaking, it requires the DM to narrate attack/spell damage in very non-intuitive ways such as "hemming in an opponent by dealing 16 slashing damage, which by the way doesn't cause any noticeable bleeding besides maybe a scratch, it's more a blow to their morale, finding a chink in their armor for the right moment."

 

[Rune]

I can only speak theoretically about high-level play, so I don't know how much of an issue the OP's concerns would really be for me, but it looks like the proposed house rule does what the OP wants it to do (perhaps a little too well).

My main concern in using it (again, hypothetically), would be that it is way too complicated for me to want to run. I'll take a simple formula over multiple charts any day.

In this case, I wonder if sliding save-success-scaling further toward the savee, as was entirely the case in pre-3.x D&D, wouldn't address this issue much more simply.

It would work like this:

All save DCs would equal 10 + spellcasting ability mod. No proficiency bonus. (Same DC as normal rules at 1, probably 13. Cap of 15 DC instead of 19 for characters. Monsters might have higher.)

Saving throws would still work as-is. Or, add half proficiency to non-proficient saves, if you prefer. Simple.

Alternatively, if you don't want the spellcasting DC to scale at all (to turn that dial all the way toward pre-3.x saves), set a flat 14 DC for all effects that call for saves. Even simpler.