Fighter - Two Weapon Fighting/Hex/Booming Blade

Question

So I’m in a campaign and the DM is helping out one of our players. He helped them build their character and at lvl 5 he has him doing something insane. Now I’m relatively new myself so I can’t completely come out and say why this won’t work.

Can someone please identify all the reasons why the sequence presented below won’t work?

I don’t know what kind of fighter he is but he’s Lvl 5 and is a dwarf and dial wields. I’m not sure of his feats either but I’m sure no matter what you have that this could not be possible. Here’s his 2 rounds for his big “boss fight move”:

Turn 1

Action: Cast hex.

Bonus Action: Cast Giant’s Might on self

Turn 2

Action: Cast booming blade

• Main hand Melee: 1D8 +3

• Booming Blade: 1D8

• Hex: 1D6

• Giant’s Might Passive: 1D6

Action surge: Attack with melee weapon (Extra Attack gives two attacks)

• Main hand Melee: 1D8 +3

• Booming Blade: 1D8

• Hex: 1D6

• Main Hand Melee: 1D8 +3

• Booming Blade: 1D8

• Hex: 1D6

Bonus Action: Two weapon fighting attack

• Melee weapon attack: 1D8+ 3

• Hex: 1D6

• Cast fire rune: 2D6

total roll 7D8, 7D6 +12

Answer 1

Hex is a bonus action.

Hex has a casting time of 1 Bonus Action, so the two turns here have a total of 3 bonus actions, when you can only take one bonus action per turn.

Too much damage from booming blade.

Booming blade adds 1d8 to its associated melee attack, but does not add anything to subsequent attacks. So the d8 booming you have in every attack but the first is wrong.

Two weapon fighting style?

Everything else seems right, except for possibly the +3 on the bonus action two weapon fighting. Unless they have the two weapon fighting style, they should not add their ability modifier to the damage of the bonus action attack.

We should forego Giant’s Might for now, as it is only 1d6 added damage.

The total damage should be 5d8+6d6+9 (or +12 if they have TWF style).

The whole build is probably invalid.

Everything above assumes that the character has the things you said they have. But now we need to question how they came to acquire these things.

First, 1d8 damage from our melee weapon together with two weapon fighting means the character must have taken the Dual Wielder feat. Two Weapon Fighting requires that both weapons be light melee weapons, and no light melee weapon deals 1d8. The Dual Wielder feat removes this restriction, allowing one handed melee weapons without the light property to be used.

This isn’t a big deal, except that it calls into question how this character knows hex and booming blade. Since they have to have Dual Wielder, they don’t have any other feat, and taking a feat is the easiest way for a Rune Knight fighter to learn hex and booming blade. In fact, I’m almost certain there is no way this build is even valid.

Answer 2

The player is playing a Dwarf (Custom Lineage) Rune Knight Fighter 5, and most of the things he's doing are legit.

Two feats: Dual Wielder, Magic Initiate (Warlock) (Hex, Booming Blade, ???). One gained via Custom Lineage, one gained via 4th level ASI.

Fighting Style: Two Weapon Fighting (forget the name - just lets you add str or dex to damage with offhand)

First turn spellcasting/ability activation: RAW, you cannot use a bonus action ability or spell as a regular action - they are separate. However it is a common houserule to let people 'trade down' to trade an action for a bonus action.

Note: Some DMs may not be aware you can't dual wield one handed weapons (it is a bit strange, especially for inhumanly strong berserkers and such) and may just be allowing it without the feat. But the feat allows it, and this character could have two feats (fairly easily - the +3 damage means they only have 16 str, and thus with point buy could easily have gotten there using custom lineage's +2 with no further ASI needed).

The only RAW mistakes that I can see is 1) two bonus actions on the first round 2) applying booming blade more than once.

Note on booming blade: from how booming blade is applied to the main hand attacks but not the offhand attack, i'd guess your DM/player think it is a buff applied to a weapon. That is not how the spell is written - it's a one-time thing for one attack only. This is an error, and it is adding 8 damage (on average) to this attack routine, but it is not a huge one and is not providing the majority of the damage.

Why does this seem broken/wrong/too strong?

The character is using a per-day resource (Hex), half of a per-day resource (Giant's Might, 2 uses/long rest), and their most powerful short rest resource (action surge) on top of their second most powerful short rest resource (invoking their rune). This is at the level where all these things work best - Extra Attack just came online, booming blade just got its +1d8 damage (although he'd be better off attacking normally than using it). On top of that, they spent an entire round yelling to go supersaiyan and get ready to do this.

Does that make this 'balanced'? Well, no. D&D 5e, despite claims to the contrary, is not a particularly balanced game. Some characters can very easily end up stronger than others, especially at certain tasks, or with certain limitations (such as 1 fight per short rest). Keeping everyone on roughly the same playing field mechanically, with similar opportunities to shine and look cool is part of the DM's job.

If the DM has optimized (however poorly) this player's character and everyone else is playing fairly unoptimized characters, then the overshadowing or power gap is something they should have been thinking about and making decisions based on. And, presumably, weren't.

Answer 3

The Dual wielder feat specifically allows using non-light weapons, so it is possible to get 1d8 damage from two weapon fighting. You can dual wield longswords or rapiers with this feat.

The main problem with the mentioned sequence of events is that casting booming blade is an action, and allows for only ONE melee attack. So you can't multiattack with booming blade. Even with action surge, you could do two booming blade actions, but not more than that.

Answer 4

I see mainly 2 flaws in the action sequence itself, plus 1 more in the build (at 5th level).

1. The first round uses two bonus actions. This would work in my world, since I allow characters to use a bonus action for their main action, but RAW this is not allowed.

2. Second round: the Booming Blade only applies to the first action. On his Action Surge, he can either take the two swings, or cast another Booming Blade and take one swing, but not both. And if he uses the Booming Blade again, he has not taken an attack action, and thus won't get the offhand attack with the 2nd weapon.

So the total roll becomes: 5D8 + 7D6 + 12, for an average of 59 hp of damage, assuming every swing hits. Plus more if the BBEG misses his save on the Fire Rune, and/or moves and takes more damage from the first Booming Blade.

The build is almost possible. It's a very effective build, for its purpose, and is mostly legal and according to the RAW.

He has to have a 16 or 17 Strength, which he could do if he is a mountain dwarf. He would have to be a 4th level Rune Knight, with the Fire Rune, the Two-Weapon fighting style, and the Dual wielder feat taken at 4th level fighter.

BUT he would have to have multiclassed into Warlock for 1 level, to get Hex and Booming Blade, in which case, he doesn't have Extra Attack yet (but would get it next level). Or, if he has Extra Attack, he has no way to have gotten the spells, unless the DM has given him a free extra feat for some reason. So at a total of 5th level, he is doing too much, but next level he could have pretty much all of it.

So really, he is doing a little bit more than what is possible under RAW, but not a huge amount. It's a very good build, at that one thing. The main thing to remember, though, is that he's a one-trick pony. He can do that one thing well, if he can get to the BBEG with his 25' move and no special mobility abilities, past all minions and obstacles, and hasn't used up his Action Surge, Fire Rune, Giant's Might, or single spell slot before getting there.

And even then, this is a once-per-short-rest event -- even in this one fight, he has to set up for a round before he can do this, and then gets one great round, but has then used all that stuff and is back to pretty much being a regular fighter. Action Surge, Giant's Might, the Fire Rune, and his spell slot are all one-shots until a rest is taken. After that, his third and subsequent rounds look like this (assuming 6th level total, so he has gotten both the Warlock bits and the Extra Attack):

Turn 3 Action: Cast booming blade Main hand Melee: 1D8 +3 Booming Blade: 1D8 Hex: 1D6 Giant’s Might Passive: 1D6

-- OR --

Action: Attack with melee weapon (Extra Attack gives two attacks) Main hand Melee: 1D8 +3 Hex: 1D6 Giant’s Might Passive: 1D6 Main Hand Melee: 1D8 +3 Hex: 1D6

Bonus Action: Two weapon fighting attack Melee weapon attack: 1D8+ 3 Hex: 1D6

Total roll: 2D8 + 2D6 + 3 = Avg 19 hp of damage with the Booming Blade, or 3d8 + 4d6 + 9 = 35 hp of damage (with regular attacks, if they all hit), which is pretty good, but not devastating.

To compare, a 5th level wizard has two fireballs, each for 8d6 (Avg 28 hp of damage) to multiple targets from a distance -- he doesn't even have to get anywhere near the BBEG, and clears out a bunch of the minions at the same time.

Or a 5th level Vengeance Paladin, who looks like this (using the same race, Great Weapon fighting style, and GWM feat:

Turn 1 Bonus Action: Vow of Enmity (gives advantage) Action: Attack with melee weapon (Extra Attack gives two attacks) Two hand Melee (w/ GWM): 2d6 + 15 Smite (2nd lvl slot): 3d8 Two Hand Melee (w/ GWM): 2d6 + 15 Smite (2nd lvl slot): 3d8

Turn 2: Bonus Action: Hunters Mark Two hand Melee (w/ GWM): 2d6 + 15 Hunters Mark: 1d6 Smite (ist lvl slot): 2d8 Two Hand Melee (w/ GWM): 2d6 + 15 Hunters Mark: 1d6 Smite (1st lvl slot): 2d8

total roll 10D8 + 10D6 + 60 = Avg 140 hp damage (plus rerolling 1s and 2s, which is good for another 10 to 20 hp of damage)