Similar to a question posed here: Can you cast Hellish Rebuke as a reaction to damage that reduces you to zero hit points?
However, I am wondering what should happen when a condition is applied as a result of a damaging effect that forces a creature to make a saving throw. Specifically when:
- a saving throw is triggered after the damaging effect.
- a saving throw is triggered along with the damage.
The Mind Flayer has actions that fit both scenarios. The first is its "tentacles."
- When a Mind Flayer hits a medium or smaller creature with its tentacles, it deals 2d10+4 psychic damage. The creature is then grappled and
[...] must succeed on a DC 15 Intelligence saving throw or be stunned until this grapple ends.
A stunned creature is incapacitated. The incapacitated condition reads:
An incapacitated creature can't take actions or reactions.
In this case, is the damaged creature allowed to use its Hellish Rebuke reaction prior to making the saving throw or must the effect of the saving throw be resolved prior to the reaction?
Hellish Rebuke's trigger:
1 reaction, which you take in response to being damaged by a creature within 60 feet of you that you can see.
- The Mind Flayer's "Mind Blast" will force each creature in the affected area to succeed on a saving throw or
take 4d8+4 psychic damage and be stunned for 1 minute.
Here, the damage and the condition are both applied after the saving throw. Could Hellish Rebuke be triggered in this instance?