fear and booming blade combo

[Blackflight]

How would you rule the following:

A spellcaster has the warcaster feat and; booming blade, fear and dissonant whispers in his spell arsenal.

1- Dissonant whispers: The spellcaster is within 5 ft. of an enemy creature that fails its wisdom save on a dissonant whispers spell. The creature uses its reaction to run away.

a) would the spellcaster get an attack of opportunity with booming blade?
b) if yes, does the creature suffer extra thunder damage for moving?

2 - Fear:: The spellcaster is within 5 ft. of an enemy creature that fails its wisdom save on a fear spell. The creature uses its action to run away.

a) would the spellcaster get an attack of opportunity with booming blade?
b) if yes, does the creature suffer extra thunder damage for moving?

[BloodSnake'sCha]

Yes and yes and yes and yes.
It is not forced movement, just regular one so it do give OA.

[Blackflight]

Yes and yes and yes and yes.
It is not forced movement, just regular one so it do give OA.

Cool! It sort of makes fear and dissonant whispers a powerful disengage tool then

[NNescio]

How would you rule the following:

A spellcaster has the warcaster feat and; booming blade, fear and dissonant whispers in his spell arsenal.

1- Dissonant whispers: The spellcaster is within 5 ft. of an enemy creature that fails its wisdom save on a dissonant whispers spell. The creature uses its reaction to run away.

a) would the spellcaster get an attack of opportunity with booming blade?
b) if yes, does the creature suffer extra thunder damage for moving?

2 - Fear:: The spellcaster is within 5 ft. of an enemy creature that fails its wisdom save on a fear spell. The creature uses its action to run away.

a) would the spellcaster get an attack of opportunity with booming blade?
b) if yes, does the creature suffer extra thunder damage for moving?

Strictly speaking, no.

If you have War Caster, then you can cast Booming Blade (and make a melee attack with your weapon as part of casting the spell) in place of an OA, but it's no longer an OA by that point ("You can... cast a spell at the creature, rather than making an opportunity attack"). This is important for features that specify they only work with OAs, like the "speed drops to 0" portion of Sentinel.

(Note that the "negate Disengage" part of Sentinel still works.)

But yes, to answer what you mean to ask, if you have War Caster, you can cast Booming Blade as a reaction against any hostile creature whose movement provokes an OA from you.

[BloodSnake'sCha]

Strictly speaking, no.

If you have War Caster, then you can cast Booming Blade (and make a melee attack with your weapon as part of casting the spell) in place of an OA, but it's no longer an OA by that point ("You can... cast a spell at the creature, rather than making an opportunity attack"). This is important for features that specify they only work with OAs, like the "speed drops to 0" portion of Sentinel.

(Note that the "negate Disengage" part of Sentinel still works.)

But yes, to answer what you mean to ask, if you have War Caster, you can cast Booming Blade as a reaction against any hostile creature whose movement provokes an OA from you.

I am curious, how you got a "no"?

[NNescio]

I am curious, how you got a "no"?

Strictly speaking, one cannot "get an attack of opportunity with booming blade" (assuming it means "opportunity attack"), even with War Caster, because it ceases to be an opportunity attack when you substitute the spell for an OA. It's a reaction spell (converted from an action), not an OA, even if it happens to share the same timing ("When a hostile creature’s movement provokes an opportunity attack from you...").

Functionally though, it's pretty much the same as "OA with Booming Blade", except for things that specifically only works with OA, like (that one part of) Sentinel.

[BloodSnake'sCha]

Strictly speaking, one cannot "get an attack of opportunity with booming blade" (assuming it means "opportunity attack"), even with War Caster, because it ceases to be an opportunity attack when you substitute the spell for an OA. It's a reaction spell (converted from an action), not an OA, even if it happens to share the same timing.

Functionally though, it's pretty much the same as "OA with Booming Blade", except for things that specifically only works with OA, like (that one part of) Sentinel.

Ok, got it
I have to say I never noticed it. It's means that sentinel doesn't desynergies with BB.

Thank you for the explanation :)

[NNescio]

Ok, got it
I have to say I never noticed it. It's means that sentinel doesn't desynergies with BB.

Yep, you (usually) don't want that part of Sentinel kicking in then. But the "lol you can't Disengage from me" part still works, to your advantage.



Thank you for the explanation :)

You're welcome.

[DigitalCharlie]

So, I played a character built around this shtick from 1-20 and about 2/3 of my DMs said it didn't trigger and 1/3 said it did. The decision was by no means game-breaking and the power of the combo is plenty valuable either way because most of the time provoking a bunch of OAs was worth it, and the bulk of the time the enemy either had to stay away for a turn or take that damage. So, while knowing the bonus damage will occur immediately can be nice, don't let it dissuade you from the combination.

That said!

There's been a bit of debate about whether dissonant whispers counts and I think that it does not trigger the movement clause of booming blade. Booming blade says that a creature must willingly move — dissonant whispers forces the enemy to move. Fear has a similar issue.

This is distinct from opportunity attacks, where the reason OAs trigger from those spells is because they use the creature's movement. The reason forced movement from something like thunderwave doesn't trigger is this line: "You also don’t provoke an opportunity Attack when you Teleport or when someone or something moves you without using your Movement, action, or Reaction." Dissonant whispers does use the creature's movement and reaction, but that movement is not willing. Fear uses the action and movement.

There's plenty of room for discussion, though, because those effects are mental enchantments that one could pretty easily argue are making a creature decide to do something. That, to me, is more persuasive for fear than it is for dissonant whispers.

[CheddarChampion]

To summarize the discussion above for anyone new, the combo works but using war caster+booming blade doesn't count as an opportunity attack for things like the sentinel feat.

[DigitalCharlie]

That's the discussion up to my post — my post is why many DMs rule that the part 1.b. of the combo does not work. There's a distinction between forced movement and forced movement that uses movement/action/reaction.

It's based partially on this sage advice from Crawford (obligatory disclaimer about not being binding): https://www.sageadvice.eu/2016/05/28/would-you-take-damage-from-booming-blade-if-you-fail-a-save-against-dissonant-whispers-and-move-away/

[Aimeryan]

There isn't actually a written definition in the books of what willing means. There isn't even a written definition of what movement means - just that you have a speed and moving costs that speed. You could easily conclude that any slight movement of choice - turning your head, for example - could set off Booming Blade. Alternatively, since this doesn't cost movement speed you can conclude it isn't movement. The latter is the widely accepted position.

The interpretation on forced vs. willing movement I see mostly circulated is something like this:

If you are on a moving horse, falling due to gravity, being propelled by strong winds, shoved by someone, etc., these are counted as forced movement - you are not moving under your own power. You may actually be very willing to move in that direction - it still doesn't count as willing movement.

By contrast then, willing movement just means movement under your own power; essentially, anything that costs movement speed*. It doesn't matter why you are moving under your own power - a T-Rex is charging at you, you are late to a meeting, your gym teacher is shouting at you, etc. - just that you are.

Therefore, since Dissonant Whispers and Fear cause the target to move under their own power it is classed as willing movement.

~~~

*Prone to standing is a possible exception - it is somewhat debated whether this is movement or not.

[Warlush]

As a DM I rule that it triggers the damage. If someone has invested a feat, a cantrip, one or two known spells, and a decent physical stat/weapon proficiency they should get to do the thing they want to do. And if they want it to count for Sentinel or Mage Slayer, then it counts. That's another whole ASI spent on this one specialization. AL shouldn't be the standard. It's too restrictive. Even to the point of inhibiting role play.

[DigitalCharlie]

I'm not wedded by any means to a particular outlook — I'm mostly just clarifying that it is not an absolute cut-and-dry it works or it doesn't. It's a good thing to talk about with a DM and ask how they're going to rule, and I should have included that's what I was going for in the first post.

As I said above, I know how I'd rule in a vacuum, but I'm also sympathetic to exactly what Warlush said. If a player asked me how I'd rule, I'd probably go with whatever they preferred.

AMAimeryan, I have a question based on what you describe in terms of mounts. Does this mean that if an enemy riding a horse was hit with booming blade, and the horse as a controlled mount moved, it wouldn't trigger booming blade's additional damage? I understand that interpretation by the rules, but something about it feels wrong.

[Aimeryan]

AMAimeryan, I have a question based on what you describe in terms of mounts. Does this mean that if an enemy riding a horse was hit with booming blade, and the horse as a controlled mount moved, it wouldn't trigger booming blade's additional damage? I understand that interpretation by the rules, but something about it feels wrong.

Yeah, as the horse was the one that moved, not the rider.

Personally, I dislike the whole 'willingly' part of Booming Blade; the sheathe of thunderous energy is not meant to be psychic or enchantment - it shouldn't know the target's mind. I would prefer if the area was saturated in the energy and anything moving into/out of that area triggered the damage on all in that area, but eh.

[Blackflight]

Thanks for the replies guys! I appreciate it.

Another question:

Say you were to spend your action casting booming blade, bonus action quicken a dissonant whispers (enemy creature fail´s it´s save), use your reaction to cast booming blade

q) does that creature take 2x booming blade damage for moving?

[Aimeryan]

Thanks for the replies guys! I appreciate it.

Another question:

Say you were to spend your action casting booming blade, bonus action quicken a dissonant whispers (enemy creature fail´s it´s save), use your reaction to cast booming blade

q) does that creature take 2x booming blade damage for moving?

Yes and no; the spells can overlap but the effects cannot (https://www.dndbeyond.com/sources/basic-rules/spellcasting#CombiningMagicalEffects). In practice, this means 'moving' once will trigger one of the spells (the most recent, technically), then 'moving' again will trigger the other.

If using a grid, the books (PHB, pg 192) recognises movement as occurring in increments of 5ft (or 'squares'); so move 5ft and trigger (and end spell #1), move another 5ft and trigger (and end spell #2). If not using a grid, the books seem to suggest you move 'foot by foot', so these would be the increments to trigger by.

[Reynaerde]

A spellcaster has the warcaster feat and; booming blade, fear and dissonant whispers in his spell arsenal. The mini guide in my signature below might interest you (I had a lot of fun writing it).