0

According to this - Is it possible to Twin Spell Dragon Breath or Booming Blade? We can Twin the booming blade spell

Now if I pick

  • 2 lvls in Fighter to get action surge
  • 3 lvls in Sorcerer to get Metamagic and then 1 more to have enough for my plan
  • Get the twinned spell and quickened spell metamagic options

We have 1 action surge, 4 sorcery points and a Booming blade cantrip I should be able to now use my standard action to cast booming blade then Twin it for 1 sorcery point, quicken another one for 2 points, then use action surge and twin the cantrip again.

This results in 5 weapon attacks in a row (Yes we did just deplete our resources from both classes, but it's possible)

The final result is 5 standard weapon attacks which will each have another 1d8 Thunder damage added onto them from the cantrip and possibly per each adding 1d8 if they move willingly (Although this effect might not stack, if anyone finds out if it does, please put the source in your answer)

Now, yes you can't exactly target a single creature with all those attacks, but it still seems a little broken.

That's why I want to ask if there isn't something I've missed or is this really possible?

The potential damage provided all attacks hit and the caster is using a great weapon (like a Maul or a great axe) would be 3d12+3d8 (+3d8 if the target moves afterwards) and 2d12+2d8 on an adjacent target, if I understand this right.

Akixkisu
  • 19,584
  • 13
  • 80
  • 138
Nuloen The Seeker
  • 738
  • 6
  • 16

2 Answers2

15

This works, but it is far from powerful

You mentioned yourself that in just one round, you depleted all your Sorcery Points for the day, and you need a short rest to regain your Action Surge.

Triggering Booming Blade when you want1 is close to impossible, especially after the tweet from Jeremy Crawford, excluding Dissonant Whispers and the like.

Comparison

A 5th level Fighter can make 2 attacks with said Maul round after round, doing 2d6+4 damage per hit. This is 11 damage on average per hit, 22 per round. In the first round, he also uses his Action Surge for 44 damage.

You do 5 attacks in one round, 3x 2d6+3+1d8 2 for 43.5 on average into the first target, and 2x 2d6+3+1d8 halved3 for 14.5 to the secondary. On subsequent rounds, you do 14.5 damage.

So in the first round you only outperform the Fighter of equal level if there is a secondary target in range, and fall way behind on subsequent rounds. Your total damage for the first three rounds is 87, his is 88.
This does not even take into account you have smaller hit chance, as you did not receive an ASI like the 5th level Fighter. Also, he can repeat this after a short rest, while you need a long rest.

This is a lot of effort for less than mediocre results.

Not a completely bad idea

With Green-Flame Blade, the calculation looks like this:
Both targets take as much damage from the primary attacks as with BB, but there is secondary damage. 2x 1d8+3 to the primary target, 3x 1d8+3 halved to the secondary. That is 26.5 additional damage, so the Fighter takes 3 more rounds to catch up.

The famously effective Sorcadins use a variation of your proposal.

  1. While I have never seen a Booming Blade triggered, this is mostly because no one I know takes it. You are at the mercy of the DM; if he likes you, BB is great.
  2. one ASI behind, I do not expect a Sorcerer to increase Str with the ASI
  3. as accepted on the now non-existing WotC forums, attacks to secondary targets are counted as 50%, as two ogres at half hit points do twice as much damage as one dead and one alive. Spreading damage is mostly (95% of the time) is a bad idea. Not always having a second enemy is just one more reason
András
  • 64,090
  • 38
  • 198
  • 422
  • Comments are not for extended discussion; this conversation has been moved to chat. – V2Blast Jun 23 '19 at 21:58
  • 1
    What secondary target? – Davo Jun 24 '19 at 02:41
  • 1
    A 5th level Fighter who does two-weapon fighting could get 5 attacks (2 from Extra Attack, 2 from Action Surge with Extra Attack, one from bonus action with second weapon) instead of just four attacks. While this would probably be for less damage than your example, it would show that 5 attacks at this level is far from impossible. – BBeast Jun 28 '19 at 10:26
  • 2
    @BBeast or polearm master, etc – Caleth Mar 28 '24 at 12:43
  • 1
    +1 on BB relying on the DM liking you. The most effective use of it i've ever seen was as a war caster opportunity attack, where the DM ruled the movement would continue even afterwards – MissMisinformation Mar 28 '24 at 17:21
2

You Cannot Twin Booming Blade

The range on Booming Blade is "Self", and Twinned Spell specifically excludes spells with a target range of "Self".

This Means You Can Cast Booming Blade 3 Times This Round

So on your turn, you can cast Booming Blade as part of an action, and then cast it again as a Bonus Action (Since you make a melee attack as part of the spell, you can do this!) And once more on your Action Surge. [Thanks to BlckKnght for pointing out this question/answer that explain the interaction better].

Note: The spells you cast do not have to all be the same - but to cast a Bonus Action spell on your turn, all the other spells you cast must be a cantrip with a casting time of 1 Action.

With Quickened Spell, you could be casting a level 1 spell as a bonus action instead of Booming Blade. However, you can only use one metamagic at a time - so if you do this, you cannot twin the spell.

Zibbobz
  • 9,680
  • 5
  • 39
  • 79
  • I don't follow the logic of Action Surge not allowing a third casting of Booming Blade if you used Quickened Spell to cast it once with a bonus action. Action Surge just gives you a second action, it doesn't change the type of action required by whatever you do with that action. Booming Blade used during Action Surge is still a cantrip with a casting time of one action, even the second time you use an action to cast it. – Blckknght Mar 28 '24 at 20:12
  • @Blckknght It's an odd quirk with how casting a bonus action spell works in 5e - "You can't cast another spell during the same turn, except for a cantrip with a casting time of 1 action." Which oddly means you could cast a spell that requires 1 action twice if you don't cast a bonus action spell. It's weird, and within reason to houserule out as a DM, but it's in the rules like that. – Zibbobz Mar 29 '24 at 00:07
  • @Blckknght This question goes into how a PC can use Action Surge to cast a spell twice https://rpg.stackexchange.com/questions/94437/can-a-pc-cast-additional-spell-using-action-surge, and this question goes into why, without action surge, you can only cast a single spell and a bonus action spell (and why Action Surge doesn't allow you to cast an additional spell if you've already used a bonus action spell) https://rpg.stackexchange.com/questions/49532/casting-multiple-spells-in-a-single-round – Zibbobz Mar 29 '24 at 00:15
  • I think this question and its answers are the best summary of multiple-spellcasting rules. You can cast two spells (of any levels) on your turn with your action and action surge. If you want to cast a bonus action spell on that turn as well, the only change is that the two action-costing spells must be cantrips (and you can't use your reaction to cast a spell on your own turn). In this question, all three spells (the two actions and the one bonus action) are all cantrips, which works fine. – Blckknght Mar 29 '24 at 02:44
  • @Blckknght I see - I wasn't aware of that Sage Advice answer to casting an additional spell as an action - I'll need to revise my answer. – Zibbobz Mar 29 '24 at 11:17