This is pretty cool.

Uncontrollable Spell Casting

At 3rd level, you have practiced the ability to focus during fury and overcome the mental challenges of Rage. When raging you are able to cast spells and cantrips. When you cast a spell roll a d20 and follow using the table below. 

1	Spell hits an ally
2-9	Spell does not cast
10-19	Spell casts as intended
20	Spell casts without using spell slot

At 6th level 2-8 fail 9-19 success

At 10th level 2-7 fail 8-19 success

At 14th level 2-6 fail 7-19 success

Mystical Rage

At 6th level your voracious anger has extended to your spellcasting ability. When you make spell attacks you add your rage damage to the spells attack roll.

Fury Caster

At 10th level the power of your Rage now influences the speed at which you cast spells. When you cast cantrips, they now use a bonus action.

Replenishing Rage

At 14th level the power of arcana has overtaken your rage, the combination of both abilities revives your spirit mid combat. When you go into rage you regain 1 spell slot of your choice.