Hi all - 

I'm looking to see if I am implementing this correctly as both a player and DM in 5e.  "Life Drain," as an effect by certain undead, obviously replaces the old "level loss" from particularly nasty and mostly undead critters.  Here's the text of an example, a Spectre:

Life Drain: Melee Spell Attack: +4 to hit, reach 5 ft., one creature. Hit: 10 (3d6) necrotic damage. The target must succeed on a DC 10 Constitution saving throw or its hit point maximum is reduced by an amount equal to the damage taken. This reduction lasts until the creature finishes a Long Rest. The target dies if this Effect reduces its hit point maximum to 0.

The way I read this attack's impact would be as follows:

Creature A (which could be a player), with 25 hit points and no wounds, gets tagged by the aforementioned Spectre's "Life Drain" attack.

Spectre rolls 10 damage.  This reduces Creature A to 15 available hps, with 10 points of wound.

Creature A is then subject to a Con saving throw - and fails.

The way I read this is, Creature A, as a result of the missed save, has max hit points reduced by 10 (the attack's damage), to 15.  After the next long rest it will restore to 25.  Creature A also still has a 10-point wound.  This leaves Creature A with 5 hit points remaining, and a serious case of pucker factor.

I would welcome input on other alternatives or corrections, if I am misinterpreting the text of that.

Thanks - 

  A

The damage a creature takes from Life Drain and similar effects is concurrent with the maximum HP reduction.  To take your example:

Target has 25 HP.  Attacker strikes with Life Drain, dealing 10 damage.  Target is at 15 HP, and must make a Con save to avoid life reduction.

On success: Target has 15 HP, and 25 Max HP
On failure: Target has 15 HP, and 15 Max HP.

The life drain does not double the damage of the hit.  What it does do, and what many players forget it does until a particularly brutal DM reminds them, is make it far easier to die outright from the Massive Damage rule.  A barbarbian with 400 max HP on most days would require an exceptionally brutal hit to die outright from massive damage - but the same barbabrian, life-drained down to only ten remaining max HP, would die outright from a "massive damage" hit of only 20 points.  DMs running a horror-themed game, or who desire to make their undead much more fearsome, would do well to remind their players that each successful life drain draws them closer to death in more than one way.

No. A creature with 25 HP hit with a Life Drain attack that deals 10 damage would be left at 15/15 HP.

Reducing a creature's maximum HP does not itself do damage - unless it would decrease by more than it's deficit (because creatures can't have more HP than their max).

Okay, thanks both - it seemed to me somewhat quirky to have it work that way, as it seems to circularly "heal" the target of the original wound (max hp ends up = total hp, even though critter took a big smack).  But I can see the effect can be explained as instead of two separate effects (necrotic wound + max hp reduction), it can be read as one of two different severities (necrotic wound or max hp reduction).  

Thanks again - 

  T

Heh.  I sincerely doubt any player would consider the loss of ten maximum HP to be 'healing'.

Consider, instead, that it's simply an order of operations issue.  The attack happens first, and does its damage.  Then the save happens, and if the save fails the target suffers a loss in maximum HP.  The target does not suffer the loss first and then the damage.  It can't - the damage has to happen first in order to determine how much maximum HP is lost.

Yeah, that makes sense - a wound that simply refuses to heal.  I like it :).  Seriously f'd up :).

Just be aware of how it interacts with Temporary HP - because that behaves a little more like you were initially thinking.

If someone with 25/25 HP and 10/10 Temporary HP takes 10 damage from a creature with Life Drain - they do appear to take 20 HP worth of damage.
At first they take 10 damage - and that simply removes all their Temporary HP and they are left with 25/25 HP. But then the Life Drain Max HP reduction happens - which reduces them to 25/15 HP. But then they have more HP than their Max HP - and that can't happen. So they are reduced to 15/15 HP.

Essentially - the Temporary HP ended up being completely useless - and that's not a fun interaction for players. Then again - neither is having their max HP reduced.

I think life drain is great at the start of adventures to make it harder.