I'm homebrewing an aberration monster to serve as a major BBEG and endgame threat for the campaign I'm running. The monster theme is "avatar of a sealed elder God". It should be able to, at worst, survive for a decent period against a level 20 party and to ideally be an actual threat to it without having to rely on something like the banshee's scream or other insta-kill ability. Instead, I wanted to expand on the powerful eldritch monster concept, in which the monster can mentally exhaust those who are near it as its special legendary action, thus resulting in the following ability:

Exhaustion Pulse (Costs 3 actions). [redacted] emits a powerful psychic pulse. All creatures within a 30 foot radius of it must succeed on a DC 22 Constitution saving throw or gain disadvantage on attack rolls and saving throws for the next 3 rounds.

My main worry is the amount of complaints I hear about the effects of disadvantages in attack rolls and how broken they can be (such as with how the Cloak of Displacement can be a game-breaking item). With that in mind, is such an ability too terribly broken for a monster with challenge rating at around 30?

For more context, in case that's necessary, it has an armor class of 22, constitution of 23, magic resistance, and 632 (55d10 + 330) HP. It also has an average of 263 damage per round with +16 attack bonus, including one attack capable of reducing the hit point maximum of a creature by 31 on average until they long rest. It has 3 legendary actions per round. The creature is a large aberration.

As for clarification on what exactly the problem is and what I mean by "problematic": I want the battle to be challenging for everyone, but I have a feeling that this could feel more like active, targeted punishment for a PC for dealing damage at close quarters rather than an ability that actually represents a challenge for the party as a whole, even if the detriment to one character can mean a detriment to the entire group. This isn't specific for my party, but rather for any party that doesn't have exclusively close quarter damage dealers which can't remain at a safe distance.

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    \$\begingroup\$ You said this is for a campaign that is already in progress right? Do you know the party/want answers specific to your party? I imagine the impact would vary wildly depending on whether you have a Rogue who relies on advantage, casters who can be effective without making attack rolls, ranged characters who regularly avoid being within 30 ft, whether anyone has the lucky feat for super-advantage, etc. \$\endgroup\$ Aug 20, 2021 at 4:56
  • \$\begingroup\$ @stevenjackson121 no, I don't want that. The party has both close quarters and long range damage dealers. My main concern was whether this could easily turn into a frustrating death spiral for any given party should I go all out with it in a final confrontation. I feel like being hit with this once in a tactical battle could easily make the whole fight frustrating for anyone who doesn't rely solely on long range attacks, and I don't want that for my players which play close ranged attackers. \$\endgroup\$ Aug 20, 2021 at 14:29
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    \$\begingroup\$ Same directives as in Worldbuilding SE and other stack exchanges: some questions have problems that make close votes justifiable. Casting a close vote on the question for needing details of clarity without explaining what needs to be clarified however makes the vote fairly pointless, unless the actual point is to simply make sure the question is closed rather than signing what needs to be improved. \$\endgroup\$ Aug 20, 2021 at 17:52

1 Answer 1


If you have problems, disadvantage on attacks isn't one of them

The portion of the ability you're concerned about is roughly equivalent to everyone having disadvantage against your monster, always. Let's compare this to something the Dungeon Master's Guide has guidance on: Superior Invisibility.

According to the Monster Features table, a creature that can be invisible as long as its concentrating effectively increases its AC by 2. Your ability is sometimes better than invisibility, and sometimes worse.

  • It's better in cases where the player characters could normally thwart invisibility with Truesight or similar.
  • It's worse when the player characters rely on spells and other abilities that require a target they can see.
  • It's better because it doesn't require concentration.
  • It's worse because if people stay more than 30 feet away, they're safe.

In fact, that last point is crucial if you're playing with flanking rules. Characters who do their combat up close will be affected by Exhaustion Pulse, but are likely to be able to gain advantage through flanking, and will circumvent the disadvantage entirely.

I think, from this comparison, it's not unreasonable to say that Exhaustion Pulse should be close in value to Superior Invisibility. That means it will increase the effective AC of your monster by something like 2 or 3. This is not, on its own, unreasonable - the existing CR 30 monsters that we have as examples both have AC 25, which would be about on par with your monster's AC.

Normally I'd be concerned about stacking Magic Resistance on top of that, but lo and behold, both other CR 30 monsters have that (or a better version) as well.

Look at the rest of the package

There are a couple causes for concern, however. Disadvantage on saving throws is huge, depending upon what other abilities your monster (or its minions) have. If your estimate of 263 damage per round relied on saves, for example, then Exhaustion Pulse has the potential to drastically increase your damage output. Similarly, if it has access to must-save abilities such as the feeblemind spell... Well, that'll make short work of any of your player character spellcasters.

It's also somewhat concerning that the effect of Exhaustion Pulse lasts for 3 rounds. That's unusual, to say the least: typically, abilities like this will either last for a single round, or until the target succeeds on its save. It's important to note that if a target failed once, it's nearly guaranteed to do so a second time, since it has disadvantage on the save against the legendary action.

So the likely play pattern is to use your legendary actions for other things for the intervening two rounds, then on the third round do the pulse again while anyone already under its effect is likely to fail. That's going to be both frustrating and more powerful than the effect looks on its face.

Is there a better way?

I think you'd do well to look at examples of similar themes here. There's a couple ways you could intend the ability to play out, and in my opinion your wording isn't great for either of them.

This ability is a challenge to be overcome

If you want your monster to seem horrifying and unbeatable at first, but for the tides to turn in your players' favour as the battle goes on, look at the Frightful Presence ability dragons share:

A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the dragon's Frightful Presence for the next 24 hours.

Wording like this makes it less likely that this is a repetitive annoyance, and more likely that players can actually plan around it.

This ability represents inevitability

If you want a drawn out combat with your monster to be effectively futile, you've chosen the wrong condition to impose. Your Exhaustion Pulse should actually be imposing the actual exhaustion condition.

The first level of exhaustion is a minor annoyance, but anyone who understands the mechanic should be instantly terrified if they see a monster causing on-demand exhaustion. Playing the long game against this thing would be a terrible idea, and it means being in its presence isn't just problematic; it will kill you, likely within a minute or two, without ever touching your HP.

You need to be quite careful about this, though. Exhaustion is a nasty mechanic, and the best example I have of an existing monster that uses it in this way, the sibriex, has a number of safety measures to keep it from getting out of hand.

On the other hand...

This is a CR 30 monster. You players should expect it to get out of hand.

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    \$\begingroup\$ I see. Thank you very much! Not only you confirmed my fear of it easily becoming more frustrating than actually challenging, but you actually showed me a very interesting alternative to base on (I honestly never took much attention to the sibriex when looking at the creatures in Mordenkainen's tome and had never noticed such an ability). \$\endgroup\$ Aug 20, 2021 at 12:50
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    \$\begingroup\$ You might look at the mechanic in the Sickening Radiance spell in XGE, if you want to go with the 1st option, a challenge to overcome. \$\endgroup\$ Aug 20, 2021 at 14:16
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    \$\begingroup\$ I actually liked the pulse taking a full turn for the monster, since it would give the PCs a full round to either dish damage, buff, or heal without worrying about being attacked. Assuming they notice the pattern that turns the fight into more of a puzzle, where the pulse turns can be used for resource recovery actions without feeling like they are losing ground on the damage race \$\endgroup\$
    – D.Spetz
    Aug 20, 2021 at 19:22

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