Path of the Spellblaster

The spellblaster path is a unique variant of a barbarian that allows the user to forge a magic gauntlet that allows them to store spells.  Even going so far as to be able to use these stored spells while raging.  However, this subclass focuses heavily on mixing melee combat and sprinkling in magic, being a quarter caster, they use these spells to enhance themselves without giving up the melee combat aspects that make barbarians the center of the battlefield.

Spellcasting

When you reach 3rd level, you augment your innate physical power with the ability to cast spells.

Cantrips

You learn two cantrips of your choice from the sorcerer spell list that are not from the Divination, Enchantment, or Illusion schools. You learn an additional sorcerer cantrip of your choice at 10th level that follows the same restrictions.

Spell Slots

The Spellblaster Spellcasting table shows how many spell slots you have to cast your sorcerer spells of 1st level and higher. To cast one of these spells, you must expend a slot of the spell's level or higher. You regain all expended spell slots when you finish a long rest.

For example, if you know the 1st-level spell Shield and have a 1st-level and a 2nd-level spell slot available, you can cast Shield using either slot.

Spells Known of 1st Level and Higher

You know three 1st-level sorcerer spells of your choice,  none of which can be from the Divination, Enchantment, or Illusion school spells on the sorcerer spell list.

The Spells Known column of the Spellblaster Spellcasting table shows when you learn more sorcerer spells of 1st level or higher. None of these spells be from the Divination, Enchantment, or Illusion school spell of your choice, and must be of a level for which you have spell slots. For instance, when you reach 7th level in this class, you can learn one new spell of 1st or 2nd level.

Whenever you gain a level in this class, you can replace one of the sorcerer spells you know with another spell of your choice from the sorcerer spell list. The new spell must be of a level for which you have spell slots, and it cannot be from the Divination, Enchantment, or Illusion spell schools.

Spellcasting Ability

Charisma is your spellcasting ability for your sorcerer spells, since you use your innate abilities and infuse them into your gauntlet. You use your Charisma whenever a spell refers to your spellcasting ability. In addition, you use your Charisma modifier when setting the saving throw DC for a sorcerer spell you cast and when making an attack roll with one.

Spell save DC = 8 + your proficiency bonus + your Charisma modifier

Spell attack modifier = your proficiency bonus + your Charisma modifier

Spellblaster Spellcasting

Barbarian Level	Cantrips Known	Spells Known	— Spell Slots per Spell Level —
			1st	2nd	3rd	4th
3rd	2	3	2	—	—	—
4th	2	4	3	—	—	—
5th	2	4	3	—	—	—
6th	2	4	3	—	—	—
7th	2	5	4	2	—	—
8th	2	6	4	2	—	—
9th	2	6	4	2	—	—
10th	3	7	4	3	—	—
11th	3	8	4	3	—	—
12th	3	8	4	3	—	—
13th	3	9	4	3	2	—
14th	3	10	4	3	2	—
15th	3	10	4	3	2	—
16th	3	11	4	3	3	—
17th	3	11	4	3	3	—
18th	3	11	4	3	3	—
19th	3	12	4	3	3	1
20th	3	13	4	3	3	1

Gauntlet Wielder

When you take this subclass at 3rd level, you are granted the ability to store spells in a magical gauntlet you create.

You gain proficiency with tinker's tools, and you gain access to creating a Spell Gauntlet.  The Spell Gauntlet requires 10gp and 1 hour to create for the first time and if it is ever destroyed or lost.

Your Spell Gauntlet allows you to store a number of spells or cantrips equal to your proficiency bonus at the end of a long rest.  You can store a single spell multiple times so long as you have the spell slots and store slots to do so.  Equipping the Spell Gauntlet does not count as armor.  Creatures others than you cannot effectively use your gauntlet.

To store a spell, it cannot be from the Divination, Enchantment, or Illusion School and cannot require concentration.  You must expend the spell slot of the spell you want to store and you must know the spell and have it prepared.  You may use any of your stored spells while raging (but you cannot cast normal spells and cannot concentrate while raging) and they do not take any verbal or somatic components to cast.  They will take effect at the level the spell was stored at.

Spell Blast

At 6th level, you've learned more ways to intertwine your spell casting and your martial abilities.

When casting a spell or cantrip that has a casting time of 1 action (this includes spells stored in your gauntlet), you can choose to cast it in place of one of your attacks instead.  You can use this a number of times equal to your Charisma modifier (minimum 1) and the number of uses resets on a long rest.  This does not bypass the restriction of one leveled spell per turn.

Baleful Strike

Beginning at 10th level, you've learned how to shatter opponents defenses and weaken them to magical attacks when you hit them with a melee attack.

When you hit a creature with a melee attack, any time it is hit with a spell or magical weapon it must subtract 1d4 if it is a save or add 1d4 to hit.  Additionally, when you hit that creature with your next spell, you can roll advantage to hit with the spell or impose disadvantage on the save.  Using this feature again on a creature already affected by it allows you to reset the timer.  These effects last until the end of your next turn.  

Fully Charged

At 14th level, you've developed new techniques to make your Spell Gauntlet more powerful. 

While your gauntlet is fully charged, you have access to a new ability, Arcane Detonation.

Arcane Detonation. While your gauntlet is full of stored spells that have not been expended, you can choose to up-cast one of your stored spells to a spell level equal to the highest spell slot of a full-caster of equivalent level to the number of levels you have in barbarian.  This expends the stored spell.  You can use this three times per long rest.

Additionally when you land a critical hit with a melee attack, you can use your reaction to expend a spell slot and recover an expended stored spell at the newly expended spell slots level.  You can do this even while raging.