Barbarian Subclass: Mage Warden

An embodiment of raw might and arcane affinity, the Mage Warden strides the battlefield with a dedicated spellcaster at their side. Their harmony of power and magic creates a union few can challenge.

Level 3: Mage Side-kick

When you choose this path at 3rd level, you are accompanied by a mage companion.

This companion uses the Mage Sidekick Class.

Optional Choice: [This must have approval from the DM!] Beginning as a 1st-level wizard, this side-kick progresses as a wizard but can never exceed your own Barbarian level. They gain hit points equivalent to a roll of 1d6 (or 4) + their Constitution modifier per level.

Side-kick's Arcane Arsenal

Your mage side-kick can innately cast certain spells, without requiring spell slots, once per day. Furthermore, they inherently know the cantrips Guidance and Resistance:

Level 3: Protective Bond

Beginning at 3rd level, if you and your mage side-kick are within 30 feet of each other and can see one another, both of you gain a bonus to AC equal to half your proficiency bonus, rounded down.

Level 3: Mage Warden's Fury

At 3rd level, if your mage side-kick is reduced to 0 hit points but is not slain, you can instantly enter a rage without expending a rage slot.

If you're currently in a rage, its duration is extended by 1 minute.

During this specialized rage, you gain advantage on all your attack rolls and saving throws. After this rage ends, you gain one level of exhaustion.

Level 6: Arcane Surge

At 6th level, as you enter your rage, your mage side-kick can use their reaction and expend a spell slot of 1st level or higher, granting your melee weapon attacks an additional 1d6 force damage for the duration of your rage.

Level 10: Bonded Aegis

By 10th level, your bond allows you to shield your mage side-kick from impending threats.

When your mage is the target of an attack or spell, you can use your reaction to either grant them advantage on a saving throw or impose disadvantage on the attacker's roll.

If you stand adjacent to your side-kick when this occurs, you may choose to have the effect target you instead.

Level 14: Channeled Assault

Reaching 14th level, your mage side-kick can infuse your attacks with arcane power.

Using their reaction and expending a spell slot of 1st level or higher, your next successful attack deals an extra 1d8 damage of a type chosen by the mage: fire, cold, acid, poison, or lightning.

This additional damage increases by 1d8 for each level above the first that the mage expends.

Level 18: Eldritch Symbiosis

Upon achieving 18th level, your deep connection with your mage side-kick fully blossoms.

Once per long rest, when you enter a rage, you can activate this profound bond:

• Spells cast by your mage side-kick target you regardless of distance, provided you both exist on the same plane.
• The duration of any spell from your side-kick with a non-instantaneous effect, when cast upon you, is doubled.
• Should you be subjected to an effect that would stun, paralyze, or incapacitate you, your mage side-kick can intervene, using their reaction to negate that single effect on you.

This culmination represents the harmony of two souls, one fueled by raw might, the other by the mystic arts, together forming an unparalleled force on the battlefield.