Casting Spells while Raging- what's it worth?

[GiantOctopodes]

So, a character concept I'm working on is a Barbarian / Wizard Fire Genasi, who struggles between his inherent, burning rage, and his cool reason and logic. He has spent much of his lifetime trying to master self discipline, has learned many meditative techniques, and always tries to look at things from a purely logical perspective. Yet, sometimes, his temper gets the best of him, and he succumbs to his rage. Since I'd be using it when thematically appropriate, and him running around swinging a sword at things doesn't really scare anyone, I'd really like him during those times to let loose.

I envision him during those times as using nothing but Fire spells, and burning through all of his slots as quickly as possible while cutting a burning swath of devastation through whatever caused his ire, inevitably causing massive collateral damage in the process. Still no concentrating on spells, of course.

So, what would that ability (using spells while raging) with that limitation (must be fire spells) be worth? What would I have to give up to make that fair and balanced? A feat? Drop the "Reach to the Blaze" racials of the Fire Genasi in exchange for it? Get rid of some or all of the damage reductions normally granted by rage? Your thoughts are appreciated!

As a side note, I'm planning on having triggers for his rage, like taking damage, failing opposed rolls, failing saving throws, etc. If anyone has good ideas behind how to do that, mechanically, so that it's not just "oh, I rolled poorly, now I have an excuse for negative behavior" while retaining the core elements I'm trying to get here (volatile temperament, raging is him giving in, which is a source of shame, etc) I'd be very open to those as well

[Demonic Spoon]

I'd imagine that limitation has more to do with fluff than game balance. I would just allow it straight up, maybe with the condition that cantrip damage doesn't suffice to maintain the rage as a guardrail against sitting in the back and just using rage for DR.

The best way to do it, though, might just be to homebrew a new arcane tradition that has a rage-like mechanic usable once or twice per day. I'm thinking something like:

-No DR
-+ To spell damage in accordance with the Barbarian table, maybe a little higher
-Need to cast a spell (not a cantrip) or take damage every round to maintain the rage.

That way, you don't end up with a bunch of superfluous bonuses and proficiencies you can't use, you don't actually become weaker at the thing your character is supposed to be good at (blowing stuff up), but you still get mechanical support for the concept of incinerating your enemies in a rage.

[kaoskonfety]

from the hip, as a DM I'd allow what you describe (call it fiery rage perhaps?) as a half feat - get say +1 int or con and the ability to cast fire based spells with a duration of instant while raging.

This would not otherwise change the conditions for rage (attack or take damage or it fades, not sure if ranged or AOE spells fit the bill for keeping it going, but I suppose you could include yourself in the AOE and similar tactics).

I'm not seeing this changing your net effectiveness too much (feels in line with resilient and/or armour proficient for "power"), but it is neat.

[Eliana Solange]

I have a character very similar to this in concept, also a Fire Genasi. (So similar that others in my group asked if I had just posted this.) The character is now Barbarian 1 / Cleric (life) 1 / Wizard (Abj) 4. The cleric level represents time spent at the temple of Lathander working on controlling her rage, after having accidentally almost killed someone in a bar fight. We started playing at level 3, and just leveled up to 6 but haven't played at that level, so I don't have a ton of experience playing the character.

Here is what we came up with for the fire barbarian at level 1. Note that it exchanges the barbarian's usual weapon/Str based abilities to elemental abilities. (Note that "additional advantage" is also a house rule)

Fire Rage: In battle, you fight with primal ferocity. On your turn, you can enter a rage as a bonus action. While raging, you gain the following benefits if you are not wearing heavy armor:
• You have advantage (or additional advantage) on elemental (electricity, cold, fire, acid) saving throws.
• When you make a spell or melee weapon attack using Fire, you gain a bonus to the damage roll that increases as you gain levels as a barbarian. (+2 at level 1)
• You have resistance to elemental damage, immunity if you already have resistance.
If you are able to cast spells, you cannot cast or concentrate on non-fire spells while raging.
Your rage lasts for one minute. It ends early if you are knocked unconscious or if your turn ends and you have not attacked a hostile creature since your last turn or taken damage since then. You can also end your rage on your turn as a bonus action.
Once you have raged the number of times shown for your barbarian level in the Rages column of the Barbarian table, you must finish a long rest before you can rage again.

Spontaneous rage: In especially enraging circumstances determined by the DM, you must make a DC 5 Wisdom save or enter rage unintentionally. If this occurs, you must make a DC 10 Wisdom save or be forced to use your next action to attack the instigator of the rage with the Produce Flame spell.

For this character, the ability to cast fire spells while raging is somewhat offset by the fact that this character has 14 int, so her spell attacks and save DCs for wizard spells are on the low side, though she does have the Fire Genasi Burning Hands and Produce Flame that are Con based (Con 18). I'm not sure how the balance would play out in more traditional wizard with Int 20, Wand of the Warmage, etc.

We set the DCs low on the spontaneous rage because the character did spent time (and a character level) working on controlling it. So far that has never triggered and she will be devastated when it does, because she thinks she has it totally under control. So in her case it wouldn't be an "excuse" for bad behavior, but rather an upsetting loss of control, and she would be able to regain control of her actions after at most one turn (but would still stay in rage). I play her as having learned to normally use her rage in a controlled manner (able to rationally chose actions). If you want your character to fail it more often, raise the DCs obviously. We haven't discussed what would happen if spontaneous rage should be triggered but she is out of rages for the day.

This character is somewhat of an experiment in being a mostly-wizard tank. The abjuration wizard spells are mainly defensive and utility. We have a blaster sorcerer in the group as well as a druid/barbarian for more direct damage. Stats are Str 8, Dex 15, Con 18, Int 14, Wis 13, Cha 9 (on a higher than standard point buy) and the first ASI went to the War Caster stat. She wields a (cursed) flame-tongue rapier (finesse) and uses her innate Fire Genasi spells that are Con based for damage. (next ASI may go to bumping Dex and Wis, or I may do it in 2 steps with resilient Dex and resilient Wis). We play with modified rules that allow multiple and extended concentration spells, so Con was a high priority. The cursed weapon gives disadvantage on Wis saves. (Most of our party is currently using similarly cursed items -- we found a whole stack of magic items with that curse.)

The character is fun to play, but not especially powerful at this time. I don't intend for her to take any more barbarian levels, so her damage output is always going to be pretty small via weapons with only 1 attack, and like I said her spell attacks are iffy (except the Con-based ones) Not having resistance to weapon damage makes her not as effective a tank as a "real" barbarian (especially Bear Totem which I recently played in another game). She has a lot of utility, many ritual spells, some backup healing, and a fun back story, so I'm having fun playing her regardless. (And I'm in a large party, which helps with not having to rely on her too much for direct damage or healing.)

[Kryx]

There are some homebrew rage mages which could fit this idea.

Imo it should be somewhat like EK, but with Charisma and Sorc spell list.

[Ralanr]

I think the reason it's not supposed to work is because the character cannot focus enough to cast spells due to the overwhelming rage (because that's the rage fluff apparently).

Though I wonder how cantrips are taken, considering how they are pretty much magic muscle memory.