Would max HP reduction effects stack?

[holywhippet]

There are some monster attacks and spells which can reduce max HP on their target. eg. a vampire's bite attack or the harm spell. Would these max HP reducing effects stack with each other? For the harm spell it specifies a disease is the cause the max HP reduction, but I don't see in the rules that diseases of the same type can't stack, only that magical effects can't.

[MarkVIIIMarc]

There are some monster attacks and spells which can reduce max HP on their target. eg. a vampire's bite attack or the harm spell. Would these max HP reducing effects stack with each other? For the harm spell it specifies a disease is the cause the max HP reduction, but I don't see in the rules that diseases of the same type can't stack, only that magical effects can't.

Are you asking if a creature's Maximum Hit Points can be reduced twice? Like if a PC was bit by a vampire on a couple straight rounds?

[holywhippet]

Yes. And whether the same source of max HP reduction can be applied repeatedly. I've had it argued to me that the diseases caused by harm won't stack and thus only the strongest max HP reduction from that source would apply.

[Malifice]

They stack mate.

[Lunali]

Harm specifically might not stack with other castings of Harm, the rest will stack though, and will stack with Harm.

[PhoenixPhyre]

Yes. And whether the same source of max HP reduction can be applied repeatedly. I've had it argued to me that the diseases caused by harm won't stack and thus only the strongest max HP reduction from that source would apply.

I agree with this--if normal HP reduction abilities (ie wraiths, wights, etc) didn't stack with themselves, the "if a creature is reduced to 0 max hp" clauses on a lot of monster abilities would be useless.

Diseases are modal, however--either you have the disease (and have the reduced HP maximum) or you don't. You can't have two copies of the same disease. So harm doesn't stack with itself (and as a spell, that's already covered by the stacking rules for spells).

[holywhippet]

Diseases are modal, however--either you have the disease (and have the reduced HP maximum) or you don't. You can't have two copies of the same disease. So harm doesn't stack with itself (and as a spell, that's already covered by the stacking rules for spells).

The catch is, the rules say that spells don't stack. But the HP reduction from harm isn't a spell (since you can't dispel it) but a disease.

[PhoenixPhyre]

The catch is, the rules say that spells don't stack. But the HP reduction from harm isn't a spell (since you can't dispel it) but a disease.

I thought I covered that with the first part (about diseases being modal). You can't have two copies of any particular disease (at least not in any way that makes sense to me). While the spell itself isn't stacking (and so technically you are correct that the spell-stacking rules don't apply like I thought they did as I forgot the exact spell specification), the effect (the disease) doesn't meaningfully (to me) stack either. It would certainly stack with other max HP reduction effects, but not itself. Or at least that's how I would rule it.

[holywhippet]

I thought I covered that with the first part (about diseases being modal). You can't have two copies of any particular disease (at least not in any way that makes sense to me). While the spell itself isn't stacking (and so technically you are correct that the spell-stacking rules don't apply like I thought they did as I forgot the exact spell specification), the effect (the disease) doesn't meaningfully (to me) stack either. It would certainly stack with other max HP reduction effects, but not itself. Or at least that's how I would rule it.

I can see your points for the most past. It's just that I have to wonder if they refer to the max HP reduction of harm as a disease just as a convenient label and to outline that cure disease abilities will counter it. Normally having two copies of a disease wouldn't be relevant since there isn't much of anything to stack. But decreasing your max HP with each extra save would make sense since the spell from my point of view. The spell is literally trying to rot you away.

[RSP]

think if it this way: the HP Max is reduced for the duration of the effect. So if you have 50 max HPs and a vampire bites you, reducing your HP max by 10, you now have 40 max HPs. If another creature hits you with a HP max lowering effect, your HP max is 40 (not 50).

I’d not think of them as “stacking,” but rather, max HP lowering works just like HP lowering in general: you’re not “stacking” the effects of damage each time you get hit, you’re losing HPs.