Is this homebrew Chromatic Blade spell balanced?

Question

Honestly, this spell was my Eldritch Knight player's idea but I thought it interesting and am trying to work out the balance. It's sort of a hybrid of the chromatic orb and green-flame blade spells.

Spell Concept

The idea is to imbue chromatic orb's ability to pick the element, a powerful ability, into a melee attack with similar-ish splash damage. Something akin to the dragon's breath spell's short-range cone felt right.

Current Draft

Chromatic Blade

2nd-level evocation

Casting Time: 1 action
Range: 5 feet
Components: V, M (a weapon)
Duration: Instantaneous

Your weapon gleams with incandescent light. You choose acid, cold, fire, lightning, poison, or thunder for the type of glow you create. As part of the action used to cast this spell, you must make a melee attack with a weapon against one creature within the spell's range, otherwise the spell fails. On a hit, the target suffers the attack's normal effects, and elemental energy of that type bursts forth from your weapon in a 5-foot cone directed at the point of attack. Creatures within the cone's area of effect take 2d6 damage of the chosen elemental type.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the damage increases by 1d6 for each slot level above 2nd.

Wording clarifications for reading purposes

• "Incandescent" tends to mean "glows from being heated" (like an incandescent light bulb). The nearest alternative I could think of was radiant, and while I think that's a better fit semantically, that is already its own damage type (and intentionally not one of the options here to keep in line with chromatic orb). I could just say "chromatic light", but chromatic is just the light spectrum already so that's lame/nonsense.

• "directed at the point of attack" is a little awkward, but the intent is "from you in the direction of the attack". Unsure on the best wording there to represent this.

• "Cone of 5-ft. radius": The intent of the spell is to represent an area like so:

   | | |X|
   |O|X|X|
   | | |X|
  

  With the O being the caster, and the Xs being the targets. So the cone would include the hit target of the melee attack (like green-flame blade) and proceed to jump to the 3 adjacent/back tiles (back, diagonal up, diagonal down). If there's a better way to word that part in general, I'd be open to it.

Balance considerations

My thinking was that being able to pick your element is a powerful feature of chromatic orb, and giving it an AOE effect both warranted it dealing less direct damage than the nearest equivalents (1 casting of chromatic orb and 1 spray of dragon's breath). Math comparisons of similar abilities/attacks/spells:

• chromatic orb: 1st-level spell, does 3d8 of chosen type to a single target based on spell attack roll (averaging 13.5 on a hit)
• dragon's breath: 2nd-level spell, does 3d6 per breath (average 10.5 per target) but with a save so at least some guaranteed damage (average 5.25 on a save per target) and across a 15-foot cone (bigger area than proposed)
• dragonborn breath weapon: once per short rest and character-specific (like from a red dragonborn), does 2d6 of your draconic ancestry's elemental type (average 7 per target) with an associated save for half damage (average 3.5 per target) for a 5-foot cone (same area)
• scorching ray: 2nd-level spell, 3 individual ranged attack rolls for 2d6 fire damage per hit (average 7 per hit)
• green-flame blade: cantrip, melee hit + fire damage on additional creature within 5 feet based on your spell modifier (1-5 realistically)

All of the above scale to include an extra damage die per level, or in the case of green flame blade, being a cantrip, at select player levels.

Alternatives/options speculated

• Could perhaps use a save for the elemental damage, Dex or Con respective to the element chosen like normal)
  • Pro(s): fits closer to the dragon's breath spell's damage per target (also 2nd level)
  • Con(s): spell already requires a struck melee attack before it does anything and that then means its a roll per target, which I know lots of spells do but just adds to the complexity of the mechanics
• Could make it just a single additional target within 5ft of the melee attack target.
  • Pro(s): Would make it fit a little closer to Green Flame Blade's effect
  • Con(s): then the damage at face value seems a little underwhelming being 2d6 per target (though in its current form of not needing a secondary save for each target in the cone, it's potentially up to melee weapon + 8d6 damage in total, compared to 6d6 for all 3 rays hitting for scorching ray, and you get to pick the damage type for this, though a more realistic situation of melee target + 1 extra is melee + 4d8 chosen damage)

• Could increase/decrease the damage dealt or increase the range if the damage seems right but maybe not enough AOE (more similarly scoped to dragon's breath spell, also 2nd-level)

  Overall, is this homebrew chromatic blade spell balanced? How could it be improved?

Answer 1

This is a great start

I always love when player's have a idea for a unique ability they want for their character so even if this was slightly over-powered I would consider allowing it. Overall it looks pretty good and I think you've done a good job and thinking through the balance of the spell overall. I'll just highlight a few things that I noticed from reading it.

"Incandescent light" is ambiguous

While I thematically understand what you were going for. Emitting light is a mechanical term in D&D and "incandescent" isn't one of the types. It would be better to simply stick with "dim light" or "bright light" and specify a distance. Or if you don't intend for it to emit light, consider rewording or removing this entirely.

The area of effect is wrong

A 5 foot cone would only hit the first target. I think the correct area for the effect you want is a 10 foot cone originating from you and directed toward the target of the attack.

Damage is underwhelming

For a second level spell the damage isn't that spectacular. Of the spell you compare it too, Scorching Ray has significantly more range and Dragon's breathe has up to 10 activation per casting. I think you could consider increasing this, consider spells such as Burnings Hands and Ice Knife in your comparison.

No save for additional targets

Basically this is a AoE spell that only requires an attack roll against the closest enemy in the range. If used cleverly you could attack a low AC target and have a high AC target as one of the additional targets which would then take automatic damage. Instead I would consider something like the Ice Knife mechanic where the additional effect is trigger hit or miss but allows a saving throw for half damage.

Missing the attack roll is a big cost

Currently there is a huge opportunity cost to cast this spell. Assuming the fighter is at least level 5 they are giving up their extra attack and a second level spell slot for the chance to do some extra damage. If they miss the attack roll it is all wasted.

I would suggest either activating the effect hit or miss as mentioned above or looking at the Paladin's smite spells that activation on the next melee hit instead of as part of the action to cast it.

Conclusion

I like the spell overall, I think its a good start. And while I think it could be improved I don't think it is so unbalanced that I would ban it at my table. If you do make changes remember that each of the comments I made were to that issue in isolation. Some of the issues are related so if you modify one consider how it effects the others.

Good luck and remember to wait at least 3 days before posted an new iteration to give time for multiple answer to come in.

Answer 2

Needs some work, but interesting concept

The spells that seem similar to me to balance against are the Smite spells (with effects on hit) and elemental weapon.

The problem is that you are kind of combining both of these, and I think the spell level is too low because of it.

The 2nd level smite spell is branding smite which starts 2d6 damage and then has a continuing rider removing a condition (invisibility) as the concentration effect.

Elemental Weapon is a third level concentration spell that turns a nonmagical weapon into a +1 weapon and adds another 1d4 damage of the elemental damage type you choose.

My reasoning for including elemental weapon is the inclusion of elemental damage. For monsters that the character knows are vulnerable or resistant to damage they are already dealing, this is a big deal. That freedom of choosing damage type is not something to be ignored.

Your spell seems to merge the two by adding 2d6 damage of your type choice and then instead of a condition rider, it turns into an area effect.

The latter aspect of that is a big deal - especially for melee weapon casters that may not have a lot of area effect options. It's situational, but 2nd level feels a bit low and I think this is more of a 3rd level spell to put it with elemental weapon. It deals more damage, but only one attack, so I think that's the balance there.

Answer 3

Unavoidable damage is problematic

Running through similar options that come to mind, in rough order of avoidability:

• Cloud of Daggers (2nd level, 4d4 magical slashing AOE, no counter-play)
• Heat Metal (2nd level, 2d8 fire, Don't wear armor as counter-play)
• Magic Missile (1st level, 3d4+3 force, Shield as counter-play)
• HP-limited (e.g. Sleep, Power Word Kill, Don't be weak as counter-play)
• Walls (e.g. Fire, Prismatic, Don't walk into them as counter-play)
• AOE blasts (Usually save-for-half, Evasion as counter-play)
• Reactive (e.g. Armor of Agathys, Stop hitting me as counter-play)
• On-hit effects (e.g. Hunter's mark, requires hit, Don't get hit as counter-play)

As you can see the only thing even close to your blade is Cloud of Daggers, which is a bit of a funky spell already, and deals magical slashing damage. Being able to choose an arbitrary element (nothing I know of is immune to all of the above, even Slaadi are acid, cold, fire, lightning, and thunder) means you can deal guaranteed damage (albeit small amounts of it) by tossing an unconscious rat into the air in front of you, which seems bad.

Unfortunately...

Rolling for AOE on-hit effects is also problematic

Worst case it is only 3-4 rolls, but it still is also unprecedented and slows down combat for an extra 7 average damage.

Best bet - leave it as-is and reserve the right to change if abused

I think it is a neat effect and idea, and it's your game!