Being a barbarian is fun, but sometimes it can be nice to mix things up. Take a break from all the raging and smashing and cool down with a few levels of another class. However, not all classes mesh well with barbarians. Here’s a guide for what works and what doesn’t.
Artificer
There’s not much here. Artificers are focused on utility and barbarians are not. Barbarians can’t cast spells while raging, and artificer spells don’t help barbarians most of the time. Level 2 infusions can have value, but mostly for the +1 weapon or +1 shield infusions, and that’s a waste of two whole levels if your party finds, say, a magic weapon or shield.
Bard
The Bardbarian is a much better utility multiclass. Barbarians can take three levels in bard, which gives them useful spells (utility, since barbarians won’t need damage spells), Bardic Inspiration (usable during rage and a good use of bonus actions), and the College of Swords subclass (which increases burst damage). Adding Expertise your Athletics skill makes your Bardbarian a great grappler too.
Cleric
Barbarians can’t cast spells during rage. That wording is very specific, they can’t cast spells. Clerics get a lot of early-level abilities that aren’t spells, which means that they have a lot of synergy with barbarians. Depending on how you’re building your barbarian, you can take one or two cleric levels. One level gets spellcasting and a subclass ability, two levels get Channel Divinity. Aggressive cleric domains are good for this; War Domain gives a number of extra bonus action attacks and attack roll bonuses, and Death Domain gives a little extra damage. Path of the Storm Herald barbarians synergize especially well with Tempest Domain barbarians. Plus, this gives access to the entire cleric level 1 spell list, letting you have access to some emergency healing.
Druid
Druid is the most powerful spellcaster class to dip into as a barbarian. You should take at least two levels and choose Circle of the Moon to get the Combat Wild Shape ability. Rage persists when you use Wild Shape, so you can easily rage, turn into a Dire Wolf, and go to town on an enemy. It can even be beneficial to take a third level of druid to get significantly more spell slots. This can seem counterintuitive because barbarians can’t cast spells while raging, but Circle of the Moon druids can expend spell slots (not cast spells) to self-heal during Wild Shape, making you the tankiest furry in the game.
Fighter
Multiclassing into fighter is simple, but good. Fighter abilities are good for barbarians up through level 3, so it’s worth taking 1-3 levels depending how much you want to commit. Taking the Dueling or Great Weapon Fighting styles are great depending on what weapon you use. If you take three levels, both the Battle Master archetype and the Champion archetype are good, offering combat moves or a wild amount of crits, respectively.
Monk
Not worth it. Unarmored Defense doesn’t stack, and using Dexterity for monk weapons doesn’t proc extra barbarian rage damage. There is nothing good about this multiclass.
Paladin
This option is decent. Dipping one level into paladin is strictly better than dipping one level into fighter; it has the same good powerful weapon fighting styles, plus emergency healing and a free utility power. Two levels gives minimal spellcasting and Divine Smite, which is nice bonus damage but won’t scale. There are some interesting options at three paladin levels, but none that are worth the investment.
Ranger
Not a great option. The level one abilities can work well for roleplaying a barbarian tracker, but are otherwise not amazing. The fact that you can’t get a fighting style until 2nd level is not ideal, especially when it doesn’t include Great Weapon Fighting. Also, so much of ranger combat potency relies on hunter’s mark, which barbarians can’t use during rage.
Rogue
Multiclassing into rogue is a mixed bag. Again, expertise allows any barbarian to become an expert grappler. However, Sneak Attack damage is only okay, since it requires using a finesse weapon. If you’re willing to be the only rapier-wielding barbarian you can still use it, but since the damage scales with rogue levels, it will lag at higher levels. On the other hand, Reckless Attack guarantees that the Sneak Attack damage will apply. Putting a second level into rogue gives Cunning Action, which is mostly useful for the extra dash that allows barbarians to chase down enemies and maintain rage.
Sorcerer
If you want to multiclass into sorcerer, take only one level and take it for the flavor and utility of the Sorcerous Origin abilities. The Wild Magic, Divine Soul, and Shadow subclasses are good for this. Still, if you want Wild Magic as a barbarian, check out the Path of the Wild Soul subclass in Unearthed Arcana.
Warlock
Like the sorcerer, it’s only worth taking one level of warlock for the subclass abilities. However, one subclass stands ahead of the crowd, the Hexblade. The Hexblade’s Curse ability grants bonus damage which scales with proficiency, meaning it will keep up even when you level up as a barbarian, and twice as many crits, which is compounded by the advantage granted by Reckless Attack.
Wizard
This is nothing. The first level is only spellcasting, which barbarians can’t use while raging and none of the second-level abilities are good enough for a barbarian to justify a less-than-useful first level.