When is the Saving Throw rolled for an Infernal Wound?

Question

This came up in a game I was running yesterday.

Two devils (Bearded and Horned) in 5e have weapons that deliver "infernal wounds", which are basically bleed effects. The creatures can be found in the Monster Manual, pgs. 70 and 74, respectively, or here and here.

For convenience, here's the full text of the ability (Bearded Devil version, bold emphasis mine):

If the target is a creature other than an undead or a construct, it must succeed on a DC 12 Constitution saving throw or lose 5 (1d10) hit points at the start of each of its turns due to an infernal wound. Each time the devil hits the wounded target with this attack, the damage dealt by the wound increases by 5 (1d10). Any creature can take an action to stanch the wound with a successful DC 12 Wisdom (Medicine) check. The wound also closes if the target receives magical healing.

The Horned Devil version coincides word for word with this one, except that the wound damage is 10 (3d6) instead of 5 (1d10) and the Saving Throw DC is 17.

That said, me and my players disagreed over what was the correct interpretation of this rule, namely as to when the save should happen. There are two possible interpretations and both seem grammatically correct:

1. If the attack hits, the target is wounded, no save rolled. At the start of each of its following turns, the target rolls a Con Save, taking damage only on failures.
2. If the attack hits, the target rolls a Con Save. On a failure, it is wounded and will take damage on the start of each of its following turns, no save rolled.

Is there any official ruling on what is the correct interpretation?

Answer 1

If the target is a creature other than an undead or a construct, it must succeed on a DC 12 Constitution saving throw or lose 5 (1d10) hit points at the start of each of its turns due to an infernal wound.

As you have noticed, there are multiple ways to read this.

(succeed on a DC 12 Constitution saving throw) or (lose 5 (1d10) hit points at the start of each of its turns)

(succeed on a DC 12 Constitution saving throw or lose 5 (1d10) hit points) at (the start of each of its turns)

both are within the bounds of possible parsing of this English sentence.

But when parsing sentences in English, when there is ambiguity and no strong reason not to, you should also pay attention to order. The second parsing, while valid, requires that the events occur in an order that isn't the same as the describing sentence. So all else being equal, we treat it as a less likely interpretation.

So go with the first reading; you make a saving throw. If it fails, the "or" condition occurs.

Now, if there was a reason why the second reading was more plausible, you might go with it instead.

There is a mechanical reason to use the first reading as well. If you do the save-on-hit, you reduce the total number of save rolls, and it permits combining of Infernal Wounds from multiple creatures with different DCs easier; just accumulate damage dice, as instructed:

Each time the devil hits the wounded target with this attack, the damage dealt by the wound increases by 5 (1d10)

Without that, being hit by a DC 12 1d10 wound first would could a DC 17 3d6 wound attack less dangerous! The stacking rules would still apply, but nothing says the DC changes.

Answer 2

Things do what they say they do in order.

When an attack lands, the hit condition is satisfied. A creature must then do what is in the hit text. In this case, the target now must succeed on a DC 12 Con Save or suffer an infernal wound. Not all hits lead to infernal wounds. Think of this as an if/then statement. If the target succeeds, nothing happens. If the target fails, generate the effect.

There are effects that happen immediately without saves, most notably grapples and restrains. These simply state "if the target is size x or smaller they are grappled and/or restrained". They then set a condition of how the target can relieve the condition. So their if/then statement occurs after the effect.

Narratively, this could play out in a manner of ways. For instance the bearded devil could have used the false edge of their glaive and slammed the character with it. A minor cut maybe, but nothing like a vicious slash they could have delivered otherwise that would continue to bleed due to the devilish workings of their weapon.

Answer 3

The second one. The wording is similar to bearded evil other attack, Beard attack, a part from the undead or construct exclusion. The condition to end the effect is clearly stated, and it makes little sense to make the player roll at each turn for an open wound, I think.