[RPG] Mage Slayer vs Hold Person


Interesting scenario was posed to me by one of my players.

A fighter with the mage slayer feat is within 5 feet of a mage who casts Hold Person on the fighter. The fighter fails his save (despite advantage for being w/in 5 feet) and on his turn can't act. BUT the mage then gets his concentration disrupted (perhaps another character hits the mage for damage).

Can the fighter, now "free" from Hold Person, make his feat granted reaction attack against the mage (who didn't move out of melee range)?

I figure that if it is still the same round then the fighter should be able to react, but if it is a subsequent round then whatever spellcasting related phenomenon that gives the mage slayer feat a reaction attack has passed (i.e., the fighter can't hold on to that reaction attack over multiple rounds).

And what if the mage, still in melee range, casts Hold Person on the same fighter again? Could we get stuck in a loop where the fighter can't attack?

In this case, since the feat is called Mage Slayer I would probably allow the fighter to make his reaction during the casting of the spell (possibly interrupting it) but that is just DM fiat to allow for a thematic moment and isn't my question (unless Mage Slayer is supposed to interrupt the spell while it is being cast, instead of allowing for a reaction attack afterwards [which is how I interpret the feat]).

Best Answer

If you don't meet the conditions for a reaction when (and right after) the trigger occurs, then you don't get to take the reaction.

The case you describe seems to be as follows:

  1. Fighter and Wizard are w/in 5' of each other; Wizard casts Hold Person
  2. Fighter fails save, is held (thus unable to take his reaction attack from mage slayer)
  3. Wizard does other things on his turn
  4. Time passes
  5. Fighter becomes unheld and attacks wizard for using Hold Person.

This is not permitted by the rules:

A reaction is an instant response to a trigger of some kind, which can occur on your turn or on someone else’s (Player's Basic D&D p. 70, emphasis mine).

A reaction is instant, you can't sit on the trigger for some undetermined amount of time just because you don't qualify at that moment.

The text from Ready lends credence to this interpretation:

When the trigger occurs, you can either take your reaction right after the trigger finishes or ignore the trigger (Players Basic D&D p. 72, emphasis mine).

Unless otherwise specified by an ability, a reaction does not interrupt or occur in the middle of its trigger.

The reaction happens after its trigger completes, unless the description of the reaction explicitly says otherwise (Xanathar's Guide to Everything p. 5).

So no, the scenario you describe is not possible.