dnd 5e – When is the Saving Throw rolled for an Infernal Wound?

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?