The Barbarian is a MAD (Multiple Ability Dependent) class. They require a good Strength stat for their attacks, good Constitution due to their need for a large amount of HP, and good Constitution and Dexterity for a decent AC.
From their Rage class feature (PHB, p. 47):
- You have advantage on Strength checks and Strength saving throws.
- When you make a melee weapon attack using Strength, you gain a bonus to the damage roll […]
And from their Reckless Attack class feature (PHB, p. 47):
When you make your first attack on your turn, you can decide to attack recklessly. Doing so gives you advantage on melee weapon attack rolls using Strength during this turn […]
Also from their Unarmored Defense class feature (PHB, p. 47):
While you are not wearing any armor, your Armor Class equals 10 + your Dexterity modifier + your Constitution modifier.
And finally, their Danger Sense class feature (PHB, p. 47):
You have advantage on Dexterity saving throws against effects that you can see […]
I've always been inclined to prioritise Strength and Constitution, treating Dexterity as their tertiary stat. But what about if Dexterity were their primary stat (or secondary with Constitution as their primary stat), with Strength being their tertiary (or an even lower priority) stat?
I want to optimise a Shadar-kai (PHB, p. 23 for base stats; MToF, p. 63 for subrace stats) Barbarian, who get racial bonuses of +2 to Dexterity and +1 to Constitution. Standard array or point buy. I want to put my best two stats in Dexterity and Constitution. No multiclassing or homebrew, but feats and Unearthed Arcana are OK (although I'd prefer no Unearthed Arcana if possible); hence this is not AL.
I'll assume no magic items for now (I don't want a build that is reliant on a magic item they might not have access to in play), and I'm focussing on Tier 2 levels (I'm reasoning that at Tier 1, everyone's weak anyway, and at Tiers 3-4, everyone is OP, especially if no-one has multiclassed). Also I have no party at the moment, so if that is important, assume the standard fighter, rogue, wizard, cleric with their simplest archetypes.
How could this character be effective in combat? What role could they fill? All I can think of is tank, probably with a shield and a rapier… Ideally, I'd like to optimise this character to deal as much damage as they can that does not rely on Strength, but without sacrificing their durability (AC, HP, etc) too much, since that's partly the point of sacrificing the high Strength score.
Best Answer
Your self-answer covers the standard approach well, so I'll take a stab at an alternate approach.
Dr. Hit-and-Run
Or: How I Learned to Stop Worrying and Love My Mom
Picture this: three frost giants bear down on a party of adventurers. The fighter chops away at the closest one's ankles while the rogue threads a shot between the gaps in their armor. The wizard wiggles her fingers and the giants' eyes glaze over. One swings its axe and barely misses its ally, another stares dumbly at its hands, and the final one flees. The fighter and rogue complain that the wizard should have cast fireball and wish that they had just brought along another rogue.
Wait. That's not what they would say. Without inflicting a single point of damage, the wizard completely changed the course of the fight. Damage is life, control is life insurance.
The Control Barbarian
Most Barbarian Paths focus on increasing personal defense (Bear Totem) or personal offense (Berserker). One, however, focuses on party defense: Ancestral Guardian. At Level 3, they receive the following feature (XGtE, p. 10; emphasis mine):
Combat as a control-focused Ancestral Guardian starts out like most barbarians. You rage, run at the biggest monster on the battlefield, and try to hit it in the face. From then on, your allies will scratch their heads and wonder if their barbarian is broken.
Once you hit your target, they will be harassed by a wide array of terrifying creatures; your not-mad-just-disappointed mother, way-too-much-perfume aunt, and have-I-told-you-about-my-time-in-the-war grandfather, will unite to tell your enemy why they should attack you instead of your allies.
Now that your biggest opponent wants you deader than usual, it's time to beat a hasty retreat. The Mobile feat (PHB, p. 168) lets you leave their reach without provoking an opportunity attack. Use it to stroll on over (with +10 speed from Mobile and +10 speed from barbarian's Fast Movement) to some of your smaller enemies and remind them that you're still a barbarian.
Your other allies can now engage the target of your ancestors with near impunity. Even if the harassed creature manages to hit with disadvantage, your allies have resistance to its damage. Congratulations, you just turned your whole party into Bear Totem barbarians who took the Dodge action. If the creature instead decides to chase you (assuming it can compete with your 50' speed), your allies get free opportunity attacks.
The Melee Build
The Ranged Build
Ben makes a good point in the comments - since Ancestral Protectors works at range, you can make an entirely ranged character if you want.
Instead of a rapier and shield, you just need one hand crossbow. Grab the Crossbow Expert feat (PHB, p. 165) in place of Mobile to get an additional attack (except on rounds when you begin raging). That feat also removes the disadvantage from ranged attacks while you're in melee, allowing you to still run up and tank. Later on, you can grab the Sharpshooter feat (PHB, p. 170), particularly if your party is good at generating advantage. The question requested no multiclassing, but optimally you would dip a level of fighter for the Archery fighting style.
The only thing you really lose is your shield (since you need a free hand to reload the crossbow); in exchange, you gain an additional attack on most combat turns. If you need really long range, you can easily pull out a longbow.
My Experience
One of my current Adventurers League characters is an Ancestral Guardian / Battle Master using a Strength version of this build. When I originally wrote this answer, he was an Ancestral Guardian 7 / Battle Master 3. Since then, he has capped out at Ancestral Guardian 16 / Battle Master 4. He has been quite fun to play and is extremely effective at locking down big hitters.
(This is outside the scope of the question, but don't be afraid to make a strength-based Shadar-kai. Guess what the strength score of my strength-based 10th-level barbarian is? Did you guess 16? Don't tell anyone, but I never raised it!)
How effective is he, really? The short answer is the most convincing: a wizard, protected by ancestors, survives longer than the reckless-attacking barbarian. (You obviously won't be using Reckless Attack, but the numbers are still impressive.) What follows is a condensed version of the math from my answer to "Most effective way of improving survivability for an Ancestral Guardian Barbarian".
The PCs
The Monsters
This fight will be a Deadly encounter, as it is the boss fight. The PCs will face:
A fireball from the evocation wizard will seriously injure or kill several Duergar, leaving the rest for cleanup by the warlock and the ranger/rogue. With that in mind, let's focus on the Gladiator. The Gladiator attacks three times with a +7 to hit, each dealing 11 damage on average (18 on a crit).
The Numbers
As a baseline, the barbarian will last 4.4 rounds against the Gladiator while attacking recklessly, or 6.9 rounds normally.
The wizard can last around 5 rounds if they cast shield on the first two turns of the fight. The fighter survives more than 5 times longer than without ancestors!
Conclusion
Will your dexterity-based Ancestral Guardian barbarian top the DPS charts? Nope. Will your Ancestral Protectors feature draw envious looks from control wizards? Probably. Will you have a blast running laps around enemies while your mom nags them so hard they fail at their one job? Definitely.