Life Drain and Instant Death by 'Massive Damage'

[Orion3T]

EDIT: Please note, I'm not referring to Instant Death by reducing max HP to 0. This seems a common question, but it's not what I'm asking and may be confusing some of the replies below. I am specifically referring to how Life Drain interacts with the 'Instant Death' rule due to 'massive damage', given on p197 of the PHB.

If a character is on say 10 HP with a Max of 25, and are hit with Life Drain for 20 damage, that means they are at 0hp with 10 left over, and their maximum HP is reduced to 5.

Does the reduction in max HP occur before, simultaneously with, or after the damage is dealt?

If it's at the same time, then the target would suffer Instant Death because they have 10 damage left over but their max is now reduced to 5. Or, is the damage fully applied and then their new maximum determined, in which case they are still alive (though unconscious and with a max HP of 5)?

Thanks.

[Orion3T]

For context, here's the exact situation:

An NPC (assisting the party) had taken some damage bringing him from 27 down to 12 HP. He then got hit with a critical from a Spectre's Life Drain for 26 damage.

The question is, does this cause instant death or not? A google search and searching these forums only showed discussion about the reduction of max HP to 0, which I think is perfectly clear. But this situation raises queries about the timing of the HP Max reduction.

If they are separate effects with the HP Max reduction occurring after the damage is dealt with, then he still has hope. Otherwise, he is instantly killed because he has a max HP of 1 and took enough damage to reduce him to -14 HP. Usually that would be acceptable but we aren't sure how this combines with the life drain.

[othaero]

I think you deal the damage first then his max is reduced. I would then rule that he didn't die but he would have the new max hp if brought back up.
I honestly think its a DM choice how it works but i cant think of any spell rule that says other wise. Just my 2cp

[Addaran]

I'd rule it damage first then reduce the max HP.

Reducing the max HP is just a way of saying "those damage can't be healed".

[Orion3T]

I think you deal the damage first then his max is reduced. I would then rule that he didn't die but he would have the new max hp if brought back up.
I honestly think its a DM choice how it works but i cant think of any spell rule that says other wise. Just my 2cp

Thanks for sharing. Opinions is what we are looking for really, because we are pretty sure the books do not specify how this situation is resolved. My son is DMing and is not sure how to rule.

The NPC was particularly unlucky, as the Spectre critted and then rolled well for damage. It's supposed to be 3d6 which usually couldn't kill him instantly even with the harsher ruling.

That said, the NPCs are all level 2-3 and the PCs are now level 6, so it seems inevitable the NPCs will start dying off, or perhaps deciding the dangers are beyond their abilities. So, it's probably not a big issue either way but it also might affect how I deal with the rest of the encounter.

[Erys]

If a character is on say 10 HP with a Max of 25, and are hit with Life Drain for 20 damage, that means they are at 0hp with 10 left over, and their maximum HP is reduced to 5.

Does the reduction in max HP occur before, simultaneously with, or after the damage is dealt?

If it's at the same time, then the target would suffer Instant Death because they have 10 damage left over but their max is now reduced to 5. Or, is the damage fully applied and then their new maximum determined, in which case they are still alive (though unconscious and with a max HP of 5)?

Thanks.


An NPC (assisting the party) had taken some damage bringing him from 27 down to 12 HP. He then got hit with a critical from a Spectre's Life Drain for 26 damage.

The question is, does this cause instant death or not?

Pretty sure it is at the same time.

So in the above instance, the NPC would be at 0 HP, not dead, and if/when healed would only be able to go to 1 hitpoint max.

[Orion3T]

Pretty sure it is at the same time.

So in the above instance, the NPC would be at 0 HP, not dead, and if/when healed would only be able to go to 1 hitpoint max.

If it's at the same time, then I'm not sure how that helps. It would be simultaneously:

- reduced to 0hp
- X damage left over
- a max HP of Y

This suggests to me that if X>=Y the target would die instantly.

For now, we played that he is still alive but with 1hp maximum. That's still pretty nasty. We finished for this session so don't need to decide for definite until next time we play (probably tomorrow or friday).

Thanks for all the input so far! Main thing is, neither interpretation seem blatantly wrong, so neither of us feels we are 'cheating' whatever the outcome is.

[RedGeomancer]

If the reduction in Maximum HP occurred "before" the HP damage, then every time a specter (or creature with Life Drain) hit someone at max, they would effectively lose double HP. If they take X damage, first their maximum is reduced to Max - X, then they lose X more from the new maximum.

This is obviously not how it is intended. The character takes X damage and their maximum is also reduced by X.

Many characters may have damage from other sources, or resist the Life Drain with a successful saving throw, so in many cases a character will drop to 0 hit points well before their maximum HP drops to 0. The real danger of Life Drain is that magical healing will not remove it, so your character is back in the fight but on the verge of dying if they fail another saving throw against Life Drain.

[Erys]

If it's at the same time, then I'm not sure how that helps. It would be simultaneously:

- reduced to 0hp
- X damage left over
- a max HP of Y

This suggests to me that if X>=Y the target would die instantly.

For now, we played that he is still alive but with 1hp maximum. That's still pretty nasty. We finished for this session so don't need to decide for definite until next time we play (probably tomorrow or friday).

Thanks for all the input so far! Main thing is, neither interpretation seem blatantly wrong, so neither of us feels we are 'cheating' whatever the outcome is.

I see where you are coming from. The thing is, life drain attacks 2 different tracks of damage, the current and the max (if you fail the save).

So in the case your NPC had 12 HP left from his max of 27. He takes 26 damage and fails the life drain save so: he takes 26 damage his 'current hp track' taking him from 12 to 0*, simultaneously his HP max is damage for the same amount dropping it from 27 to 1.

*=There is no damage overflow or neg HP in 5th so the rest of the damage on this track is ignored.

[Ziegander]

I see where you are coming from. The thing is, life drain attacks 2 different tracks of damage, the current and the max (if you fail the save).

So in the case your NPC had 12 HP left from his max of 27. He takes 26 damage and fails the life drain save so: he takes 26 damage his 'current hp track' taking him from 12 to 0*, simultaneously his HP max is damage for the same amount dropping it from 27 to 1.

*=There is no damage overflow or neg HP in 5th so the rest of the damage on this track is ignored.

^^^^^ This.

[Orion3T]

If the reduction in Maximum HP occurred "before" the HP damage, then every time a specter (or creature with Life Drain) hit someone at max, they would effectively lose double HP. If they take X damage, first their maximum is reduced to Max - X, then they lose X more from the new maximum.

This is obviously not how it is intended. The character takes X damage and their maximum is also reduced by X.

That's a good argument actually. I don't think it's possible to handle them simultaneously without some rule stating which takes precedence (and no such thing exists, I think). Applying the Max HP first would have the effect you describe here (effectively up to doubling their damage) and I agree, that cannot have been the intention.

That leaves applying and fully resolving the damage first, then reducing max HP. I do think this seems both more balanced (without removing Life Drain's 'teeth') and more intuitive.


*=There is no damage overflow or neg HP in 5th so the rest of the damage on this track is ignored.

Hmm... this comment confuses me.

There is the rule for Instant Death on p197 of the PHB. I don't know how you define 'damage overflow' but the Instant Death (or Massive Damage) rule to me sounds like it fits that description. And is the whole reason I'm asking this question. ;)

[Erys]

Err... I think I must not understand this comment? Yes there is - there is the rule for Instant Death on p197 of the PHB. I don't know how you define 'damage overflow' but the Instant Death (or Massive Damage) rule to me sounds like it fits that description. And is the whole reason I'm asking this question. ;)

Reasonable assumption, but a little off.

Death by massive damage is a case where you take so much damage in one hit that not only did you go below zero, you went all the way to your HP Max in the red. This really only comes into play at really low levels when a crit for 20 damage can kill you out right because you only have 10 HP max.

But outside this (somewhat rare) instance you really don't track such damage once a person drops to 0. Subsequent hits do not have damage rolls added against the persons HP, they are supposed to just cause a failed death save.

[Addaran]

Reasonable assumption, but a little off.

Death by massive damage is a case where you take so much damage in one hit that not only did you go below zero, you went all the way to your HP Max in the red. This really only comes into play at really low levels when a crit for 20 damage can kill you out right because you only have 10 HP max.

But outside this (somewhat rare) instance you really don't track such damage once a person drops to 0. Subsequent hits do not have damage rolls added against the persons HP, they are supposed to just cause a failed death save.

If you're low enough on HP, some high level threat can outright kill even higher level members, especially if they are squishy. A dragon's breath attack or high lvl damage spells can do 50-75 damage.

Also lots of chances for it to happen when there's thing that reduce max HP like in the OP. That NPC with only 1 HP max atm would insta-die from a goblin's hit.

[pwykersotz]

I see where you are coming from. The thing is, life drain attacks 2 different tracks of damage, the current and the max (if you fail the save).

So in the case your NPC had 12 HP left from his max of 27. He takes 26 damage and fails the life drain save so: he takes 26 damage his 'current hp track' taking him from 12 to 0*, simultaneously his HP max is damage for the same amount dropping it from 27 to 1.

*=There is no damage overflow or neg HP in 5th so the rest of the damage on this track is ignored.

I just want to add my belief that this quote is correct. It's not a first/second/simultaneous thing. It's reducing the capacity of the pool by the same amount that it is drained. The NPC has a new maximum pool of 1hp.

[Orion3T]

Thanks for trying to clarify.... and I don't wish to seem argumentative, but I still don't follow what point you're trying to make or its relevance to the original question (which I consider resolved at this point, and again wish to thank everyone for their help).


Reasonable assumption, but a little off.

Which assumption? My only assumption was what exactly you mean by 'damage overflow'. If you specifically meant damage overflow which is persistent and affects subsequent rounds, then I'd agree the instant death rule doesn't count as such, because it either causes death or it doesn't, and has no further effect. But just taking it literally, it fitted the description 'damage overflow'. But it seems you were using 'damage overflow' and 'negative HP' to mean exactly the same thing, in which case I see what you mean.



Death by massive damage is a case where you take so much damage in one hit that not only did you go below zero, you went all the way to your HP Max in the red.

OK, I completely understand how it normally works, and don't think I have suggested otherwise. So I'm not sure why you're clarifying? If you're saying that doesn't fit your definition of 'damage overflow' then it's all good, though I still don't see the relevance of your earlier comment.


This really only comes into play at really low levels when a crit for 20 damage can kill you out right because you only have 10 HP max.

I don't understand the relevance of this statement either - how often something happens doesn't affect how it works mechanically. It became relevant to us as a result of life drain (and the Wraith we encountered afterwards could certainly affect my level 6 characters, luckily it didn't get chance to land a hit). It's still relevant to our poor rogue NPC because he only has 1 HP max.

So, given it is relevant to us right now, I don't see the relevance of saying it only comes into effect in X situation. I'm in X situation, so the mechanic is relevant.


But outside this (somewhat rare) instance you really don't track such damage once a person drops to 0.

Right, but in this instance you do count damage dealt in excess, and it can have a massive effect. Hence my confusion why you seemed to be saying this is never done in 5e. It is.


Subsequent hits do not have damage rolls added against the persons HP, they are supposed to just cause a failed death save.

Again, this just seems wrong to me. The final sentence of the 'Damage at 0 HP' rule seems to make it pretty clear that attacking and hitting a creature on 0HP still rolls damage, and can still cause instant death. This is in addition to the automatic death save failure (or 2 failures on a crit). It's still not 'tracked' beyond that attack, but damage is still rolled.


Just to reiterate, I'm really not looking for an argument here. I appreciate you were trying to answer my question and thank you for that. But your comments are confusing me because you seem to be stating things that go directly against what I'm reading in the book. So, I'm seeking to clarify what you mean so I can better understand the rules, or perhaps if you're mistaken it will clear something up for you or remind you of rules you had forgotten about. I'm hoping the continuance of this discussion is something that can be of benefit.

Thanks again.

[Orion3T]

If you're low enough on HP, some high level threat can outright kill even higher level members, especially if they are squishy. A dragon's breath attack or high lvl damage spells can do 50-75 damage.

Also lots of chances for it to happen when there's thing that reduce max HP like in the OP. That NPC with only 1 HP max atm would insta-die from a goblin's hit.

Exactly my points. I appreciate the discussion, but I think I don't understand what Erys is trying to say, or its relevance to the OP.

[Orion3T]

I just want to add my belief that this quote is correct. It's not a first/second/simultaneous thing. It's reducing the capacity of the pool by the same amount that it is drained. The NPC has a new maximum pool of 1hp.

I don't understand. There are multiple effects and they must be resolved either in some order or simultaneously. I agree he has a max HP of 1, but there was excess damage after dropping to 0 and the question is whether that is applied to the new HP maximum or his original HP maximum (before the attack hit.)

- I can't make sense of trying to resolve them 'simultaneously' - usually it works just fine, but not where the Instant Death rule is concerned. It's important to know the max HP of the creature at the time the 'massive damage' (beyond that required to drop to 0 HP) rule is applied. Let me put it another way which removes the confusion of current HP - a creature with a max HP of 10 and currently on 0 HP is hit with Life Drain for 8 damage. Are they instantly killed or not? If both effects are simultaneous then it seems like they are instantly killed (because HP Max is reduced to 2, and at the same time there is 8 damage to take) but it seems fuzzy at best how this should resolve.

- Resolving the HP Max reduction first seems to result in clearly unintended effects as mentioned by RedGeomancer (like someone on max HP taking double damage; someone at 20/20 takes 10 damage, first reduce to 10/10 then apply 10 damage and in effect they have taken 20 damage and dropped in 1 hit).

- Therefore by process of elimination and the principle of parsimony, applying the damage first and then the HP Max reduction seems like the best way to deal with Life Drain.


I haven't seen anyone clearly argue against this interpretation, which gives me some confidence it's correct (though perhaps I'm using some badly chosen terminology to try and explain). It's what we went with last night and I'm now fairly convinced this must be the best way to handle it. It seems excessively strong if handled otherwise.

[mgshamster]

I would say they're instantly killed. Max HP is reduced, and suddenly the damage below zero is equal to their max HP, causing instant death.

Ghouls be vicious, yo.

[Joe the Rat]

Again, this just seems wrong to me. The final sentence of the 'Damage at 0 HP' rule seems to make it pretty clear that attacking and hitting a creature on 0HP still rolls damage, and can still cause instant death. This is in addition to the automatic death save failure (or 2 failures on a crit). It's still not 'tracked' beyond that attack, but damage is still rolled.

emphasis mine

Subsequent hits do not have damage rolls added against the persons HP, they are supposed to just cause a failed death save.
He's not saying the damage isn't rolled, just that the damage is not tracked beyond that roll. So you're in agreement here.

Mind you, if max crit damage would be below the character's max HP, then Massive Damage death is impossible, and you could save yourself a die roll.

[Orion3T]

He's not saying the damage isn't rolled, just that the damage is not tracked beyond that roll. So you're in agreement here.

While I see what you're getting at with the emphasis, I think when taken in context with the subsequent phrase his meaning is ambiguous at best:


Subsequent hits do not have damage rolls added against the persons HP, they are supposed to just cause a failed death save.

To me, the whole statement reads as if he meant no damage is rolled at all. But sure, if that's not what he meant then I don't have a problem with its factual accuracy.

I'm still somewhat confused as to the relevance of this exchange though. We are indeed 100% agreed on how HP and Max HP usually work - so yes, I think we are largely in agreement. But his comments on Instant Death are confusing to me at best; at first he seemed to suggest there is no such rule, then he seemed to argue it's not relevant because it doesn't happen very often, while also possibly suggesting that attacks against creatures at 0HP don't even roll damage.

I'm left wondering what exactly he is trying to explain as it seems ambiguous what he's trying to explain, or why. None of this seems relevant to the OP, which simply asked in what order the effects should resolve. On which note, there is one voice of dissent above which is interesting, though I don't really see much of an explanation as to why it works that way.


Mind you, if max crit damage would be below the character's max HP, then Massive Damage death is impossible, and you could save yourself a die roll.

Agreed - in principle you're told to roll it, but since its only effect is usually going to be to trigger massive damage it usually won't be necessary.

[Joe the Rat]

I'm still somewhat confused as to the relevance of this exchange though. We are indeed 100% agreed on how HP and Max HP usually work - so yes, I think we are largely in agreement. But his comments on Instant Death are confusing to me at best; at first he seemed to suggest there is no such rule, then he seemed to argue it's not relevant because it doesn't happen very often, while also possibly suggesting that attacks against creatures at 0HP don't even roll damage.

I'm left wondering what exactly he is trying to explain as it seems ambiguous what he's trying to explain, or why. None of this seems relevant to the OP, which simply asked in what order the effects should resolve. On which note, there is one voice of dissent above which is interesting, though I don't really see much of an explanation as to why it works that way.A lot of people come in from 2nd-4th edition, where tracking damage below 0 was part of the rules. There's a bit of a reflexive "no negatives, stop counting!" reaction in death's door topics around here.

That, and we also have a tendency to veer off on tangents in threads, especially after resolving the primary question.

[Shaofoo]

The attack says that you take damage then you make a saving throw to check if your HP is reduced, the damage is already done before the HP reduction even comes to play. Doing things in order the damage is resolved before the secondary effect is even checked.

[Nicodiemus]

I would also suggest that the life drain, being a temporary effect, would only be related to your hp pool, but the massive damage would key off of your true max hp total. But I like epic survival of underdog stories.

[Dimers]

Seeing as it comes up so rarely, I would choose to evade the issue entirely by declaring that the victim is in a coma and will need magic aid -- soon -- to get back to his feet. And then I'd probably apply a penalty to actions like Raise Dead does, once he's de-afflicted.

If your group of players can handle the barrage of movie quotes that come with it, you could call him "mostly dead". :smallwink:

[Orion3T]

The attack says that you take damage then you make a saving throw to check if your HP is reduced, the damage is already done before the HP reduction even comes to play. Doing things in order the damage is resolved before the secondary effect is even checked.

I wish I could see where in the description you get this from, as it would have meant we didn't need to ask. ;)

Far as I can tell the action description simply states the damage, and that it also reduces max HP on a failed save. The word 'then' is nowhere to be seen, which is a shame as it would make it perfectly clear!

If it's a general rule that monster actions resolve in this way (deal the stated damage first, then any additional effects) that would be handy to know. Does it actually say that anywhere though? I can't find it.

If not, it seems like a sensible house rule and might avoid complications arising from other abilities.

[Orion3T]

A lot of people come in from 2nd-4th edition, where tracking damage below 0 was part of the rules. There's a bit of a reflexive "no negatives, stop counting!" reaction in death's door topics around here.

OK, if it's a natural reaction because this has caused confusion in the past then it makes a bit more sense. But since I never played PnP D&D until 5E I find the rules on this point pretty clear.

I did notice when searching that a lot of discussion seemed to focus on what happens when HP aren't reduced to 0, but I couldn't find anything specific to Instant Death.


That, and we also have a tendency to veer off on tangents in threads, especially after resolving the primary question.

I am fairly satisfied it's been answered; although a couple of people seem to have different interpretations, I don't really see much of a basis for the alternative to resolving the Max HP reduction after the damage is processed.

Seems to me that a general rule that basic attack damage always resolves first would make things a bit clearer and cover a multitude of possible conflicts. If it's not stated anywhere (and I haven't seen it if it is) then it seems like a sensible house rule to cover any similarly ambiguous situations.

[Hawkstar]

I'd say "It's worse than that, he's dead, Jim!"

[SethoMarkus]

I'd say "It's worse than that, he's dead, Jim!"

"Damnit, Jim, I'm a doctor, not a 9th level Cleric!"

[Shaofoo]

I wish I could see where in the description you get this from, as it would have meant we didn't need to ask. ;)

Far as I can tell the action description simply states the damage, and that it also reduces max HP on a failed save. The word 'then' is nowhere to be seen, which is a shame as it would make it perfectly clear!

If it's a general rule that monster actions resolve in this way (deal the stated damage first, then any additional effects) that would be handy to know. Does it actually say that anywhere though? I can't find it.

If not, it seems like a sensible house rule and might avoid complications arising from other abilities.

Think of it like this, if the damage and effect happen simultaneously then the effect is useless because you haven't taken the damage yet. You are reduced equal to the damage taken but since you have yet to take damage then the reduction never applies.

I think we need less house rules and more common sense.

[Erys]

Edit: Actually, nevermind.

I am not going to try to explain something that is really simple to understand.

Done with daftness today and it adds nothing to this thread that seems done with anyway.

[Vogonjeltz]

Thanks for sharing. Opinions is what we are looking for really, because we are pretty sure the books do not specify how this situation is resolved. My son is DMing and is not sure how to rule.

The NPC was particularly unlucky, as the Spectre critted and then rolled well for damage. It's supposed to be 3d6 which usually couldn't kill him instantly even with the harsher ruling.

That said, the NPCs are all level 2-3 and the PCs are now level 6, so it seems inevitable the NPCs will start dying off, or perhaps deciding the dangers are beyond their abilities. So, it's probably not a big issue either way but it also might affect how I deal with the rest of the encounter.

Based on the way the ability is written (MM 279), the subject suffers damage and then makes the saving throw. Ergo, if they would not die from the excess damage based on their original maximum HP, then they would merely be unconscious. Consecutive hits would potentially kill from massive damage based on the new reduced maximum however (PHB 197).

Summary: The rogue is just fine as long as they weren't hit again.

[Orion3T]

To those who think this is obvious or common sense, I can only apologise for wasting your time due to my comprehension failure. Though, I don't seem to be the only person who didn't think this was obvious because at least a couple of people still seem to disagree.

Not that I'm one of them; there have been a couple of well reasoned explanations which make very good sense. I will hope to take that forward when dealing with similar situations and avoid the need to ask.

I appreciate the help from everyone, but especially from those who also managed to resist the temptation to make snide remarks. ;)

[Shaofoo]

To those who think this is obvious or common sense, I can only apologise for wasting your time due to my comprehension failure. Though, I don't seem to be the only person who didn't think this was obvious because at least a couple of people still seem to disagree.



People will disagree even when things are black and white. Even when the actual makers of the game tell them how it is people will still cling to their own interpretations (of course this is later followed by comment that the makers of the game are subhuman mongoloids that probably can't even wipe properly since they contradict themselves). Saying that because some people disagree then things are unclear is not so clear cut when the reason some people disagree might be because of their own bias.

Also less self flagellation and backhanded complements, it makes you seem disingenuous. If you really want to know why some people cling to "common sense" it is because such analysis sometimes triggers the munchkin alarm.

[Orion3T]

People will disagree even when things are black and white. Even when the actual makers of the game tell them how it is people will still cling to their own interpretations (of course this is later followed by comment that the makers of the game are subhuman mongoloids that probably can't even wipe properly since they contradict themselves). Saying that because some people disagree then things are unclear is not so clear cut when the reason some people disagree might be because of their own bias.

Of course. But people also disagree when things are actually unclear to them, and I'd tentatively propose that's more often the correct explanation, and the most reasonable assumption. I never claimed it was proof of anything, since it clearly isn't. I was simply pointing out that if this is something obvious, then I'm not the only person who doesn't see it as such.

I do accept the actual arguments given, and agree with the conclusion. I just disagree that it is 'obvious' or 'common sense'. I think this sums up how I feel about that quite well, and I don't just mean in this context but whenever anyone appeals to common sense (or claims something is just 'obvious'):

Common sense is not common (https://en.wikipedia.org/wiki/Wikipedia:Common_sense_is_not_common)

Put another way: Garbage in the Guise of Gumption (https://scienceornot.net/2014/02/06/the-appeal-to-common-sense-garbage-in-the-guise-of-gumption/)

An appeal to common sense not only fallacious (appeal to incredulity) but is an insult to those who disagree; to use it, is to be insulting (whether deliberate or not) and like most people, I don't always react well to that. It's also a massive red flag that someone doesn't actually have an argument to support their position. The most generous interpretation is that they have an argument, but are unwilling or unable to explain it properly.


Also less self flagellation and backhanded complements, it makes you seem disingenuous. If you really want to know why some people cling to "common sense" it is because such analysis sometimes triggers the munchkin alarm.

If I understand you correctly, then you're saying people use an appeal to common sense to try and shut up someone they think is a munchkin. Since my son and I aren't remotely competitive when playing D&D, and simply wanted to know the correct ruling so we could move on (in fact, I'd be happy to lose the NPC; we already lost several and I even killed one of them myself. It's just another chapter in the story) I'd argue they are mistaken in my case.

I take the point about appearing disingenuous. It wasn't though - I was simply admitting I might be missing something that others find to be obvious, while also pointing out I'm not the only one to do so. But I take the point that I phrased it too strongly.

I can assure you the thanks was 100% genuine, as was my dig at people who felt the need to be insulting.

[mgshamster]

Put another way: Garbage in the Guise of Gumption (https://scienceornot.net/2014/02/06/the-appeal-to-common-sense-garbage-in-the-guise-of-gumption/)


Great link. Thanks for that. I haven't seen that website before.

[nilshai]

I see where you are coming from. The thing is, life drain attacks 2 different tracks of damage, the current and the max (if you fail the save).

So in the case your NPC had 12 HP left from his max of 27. He takes 26 damage and fails the life drain save so: he takes 26 damage his 'current hp track' taking him from 12 to 0*, simultaneously his HP max is damage for the same amount dropping it from 27 to 1.

*=There is no damage overflow or neg HP in 5th so the rest of the damage on this track is ignored.

Incorrect. The damage dealt is not reduced to exactly bring a creature 0 hp. This is because the rules don't ever say so. The target receives the full damage, the only difference is, that the target doesn't go to negative hit points. If damage was reduced, death from massive damage could never happen.

Maximum hit points are reduced after damage is dealt, that is because the maximum hit points are reduced by an amount equal to the damage taken. This means you need to first deal damage, before you can reduce maximum hit points by an equal amount. There can be no equal to something that does not exist.