D&D 5E Can you twin booming blade

[Ancalagon]

As the title says.

I've read this build where someone twins booming blade - it's an... excessive... haste quicken twin combo.

Oh and they want to booming blade and smite at the same time, of course

 

[Charlaquin]

By RAW, I don’t see any reason this wouldn’t work. The only weird interaction is that you’re supposed to make the weapon attack “as part of the action used to cast the spell,” and Twinned spell doesn’t let you actually cast it again, it only lets you target a second creature in range. So, if you really wanted to rules lawyer it, you could say that you can target two creatures with the effect, “On a hit [with the weapon used as the spellcasting focus], the target suffers the attack's normal effects, and it becomes sheathed in booming energy until the start of your next turn. [etc.]” but you only get to make one attack as part of the action, so there’s no way to hit both of the affected targets. However, I would say that such a ruling is against the spirit of 5e’s tendency towards natural language. It’s the kind of ruling I would expect to see on Jeremy Crawford’s Twitter, rather than the kind of ruling I think is an intuitive interpretation of the text.

 

[Paul Farquhar]

RAW yes, you can twin Booming Blade, allowing you to weapon attack two targets, in addition to the effect of the spell itself.

It could be fluffed as a ghostly duplicate of your weapon arm attacking the second target.

 

[Ancalagon]

I found the flaw in my friend's proposed combo - he wanted to essentially booming blade 5 times in a turn, but he can't - the extra action granted by haste does not allow spellcasting.

 

[Oofta]

I found the flaw in my friend's proposed combo - he wanted to essentially booming blade 5 times in a turn, but he can't - the extra action granted by haste does not allow spellcasting.

Yeah, I was just going to say that. They could action surge and do it twice, but not haste.

 

[Esker]

Yeah, I was just going to say that. They could action surge and do it twice, but not haste.

I think as a sorcerer/fighter with Haste the maximum booming blade abuse you could do would be:
(1) Quickened BB using Bonus Action (2 SP)
(2) Twinned BB using main action (1 SP)
(3) Twinned BB using action surge action (1 SP)
(4) Regular attack (w/o BB) using Haste action

So you are getting 5x booming blade (split between two or more targets) even without Haste if you spend 4 SP. Then Haste can give you one more regular weapon attack.

 

[Oofta]

I think as a sorcerer/fighter with Haste the maximum booming blade abuse you could do would be:
(1) Quickened BB using Bonus Action (2 SP)
(2) Twinned BB using main action (1 SP)
(3) Twinned BB using action surge action (1 SP)
(4) Regular attack (w/o BB) using Haste action

So you are getting 5x booming blade (split between two or more targets) even without Haste if you spend 4 SP. Then Haste can give you one more regular weapon attack.

Twin spell's spell must target a creature other than self, it can't target a weapon. Whether or not the booming blade can be quickened is also debatable, you still need to make an attack as part of the action.

I could see the ruling on the latter may vary from DM to DM, but the former is pretty clear to me.

 

[Esker]

Twin spell's spell must target a creature other than self, it can't target a weapon. Whether or not the booming blade can be quickened is also debatable, you still need to make an attack as part of the action.

I could see the ruling on the latter may vary from DM to DM, but the former is pretty clear to me.

Well, the text of the spell does repeatedly refer to "the target", so it does seem to target one creature (and to be incapable of targeting more than one creature, unlike green flame blade). It has a range of 5', not a range of self, and no AoE component, so... RAW, I don't see why you couldn't twin it? I also don't see why you couldn't quicken it and cast it again with your action, same as any other cantrip. What does the fact that it involves a weapon attack have to do with anything?

 

[Charlaquin]

Well, the text of the spell does repeatedly refer to "the target", so it does seem to target one creature (and to be incapable of targeting more than one creature, unlike green flame blade). It has a range of 5', not a range of self, and no AoE component, so... RAW, I don't see why you couldn't twin it? I also don't see why you couldn't quicken it and cast it again with your action, same as any other cantrip. What does the fact that it involves a weapon attack have to do with anything?

As I mentioned earlier, Booming Blade does say that you make an attack with the weapon used as the material component as part of the action used to cast it. One could argue that Twinning it doesn’t actually constitute another use of the Cast a Spell action, and therefore doesn’t provide you another opportunity to make an attack as part of that action, it only lets you designate a second target to be affected by the “if you hit it with the attack...” portion of the spell. I think such a ruling would be founded on an overly-technical reading of a spell that is written in natural language, but it’s the kind of ruling I would expect Crawford to give on Twitter.

As for Quickened Spell, yeah, I don’t see any reason that wouldn’t work with BB.

 

[Paul Farquhar]

Booming Blade does not target the weapon. The weapon is a material component of the spell. You target a creature with the spell and you make a weapon attack as part of the casting action.

"On a hit the target suffers the attack's normal effects, and it becomes sheathed in booming energy"
-SCAG

Booming Blade can be Twinned, Quickened, Empowered, Subtle or Distant. It can't be careful, extended or heightened.