D&D's Most Overpowered Character Builds: Polearm Barbarian
A well-built D&D polearm Barbarian is an impressive damage dealer as well as an sturdy tank, with multiple ways to dominate the battlefield.
One of the best all-around melee builds in Dungeons & Dragons is a Variant Human, polearm-wielding, Totem Warrior Barbarian. Polearms are among the most advantageous weapon types in D&D, and the Barbarian is ideally suited to using glaives and halberds. This build derives extra use from high damage output, high resistances, and a choice between focusing on protection or mobility, and multi-classing can make it even better.
Using point-buy for statistics, this build starts with 16 Strength, 16 Constitution, and 14 Dexterity - enough to take full advantage of Medium Armor. Polearm Master should be the starting feat choice granted by the Variant Human race, as it grants an additional Bonus Action melee attack option and the ability to make an Opportunity Attack against opponents entering reach. At level 3, Bear Totem Spirit will extend the Resistance granted by Rage to all damage types other than Psychic. D&D Barbarians fighting in melee incur more risk, and the versatile Resistance of the Bear Totem provides staying power against nearly all damage types. Adding the Great Weapon Master feat at class level 4 allows taking a -5 to hit in exchange for +10 to damage, an accuracy penalty easily offset by using Reckless Attack to grant Advantage on melee attacks. From there, players in a low magic game will want to increase Strength, but if magic items are readily available, they could obtain a Belt of Giant Strength, leaving their Strength at 16, a respectable fallback in case they're caught in an anti-magic field.
For games with larger combat maps, the Mobility feat offers increased movement, which pairs with the Barbarian’s level 5 Fast Movement to give a 50-foot speed, usually enough to close to melee even on a large-scale battle map. If the DM is running an old-school D&D dungeon-based campaign, fights may take place in narrower corridors and smaller chambers, so the Sentinel feat can be prioritized over Mobility for more ways to defend vulnerable party members and potentially make more damaging offensive strikes. Once Strength has been increased to 20, for a low-magic game, or other feats vital to the build have been obtained, universally useful feats like Toughness can help give the durable Barbarian even more resilience, while Lucky can aid in a variety of circumstances (though saving throws against status effect spells are generally the best use for Luck Points).
Some multi-class options do not pair well in D&D, and a Fighter/Barbarian character might seem redundant at first glance. But it can be quite beneficial in the right circumstances, and superior to a single-classed Barbarian character. For games with regular large groups of enemies, a single level in Fighter can offer access to a fighting style from an Unearthed Arcana article, Tunnel Fighter. This style allows the character to enter a defensive stance where Opportunity Attacks do not use the character’s reaction. If a group of enemies approach a character with the Polearm Master feat who is in this stance, they can make an Opportunity Attack against each foe as they enter the character’s reach.
Knowing a D&D Dungeon Master’s style of pacing might also enable further multi-classing, as some DMs rarely run more than three combat encounters in the same in-game day. If a DM runs a larger number of encounters per day, staying primarily single-classed could be better, leaving enough uses of Rage for each battle, but for DMs who favor “short workdays,” a multi-class split such as Barbarian 8/Fighter 12 still allows access to Fast Movement and four uses of Rage, but also a larger number of attacks thanks to the Fighter’s level 11 increase to the Extra Attacks feature.
Many of these build principles could work for a different martial-oriented class, like Fighter, Paladin, or a College of Valor Bard, in D&D. If a group does not have a party Rogue, starting with a single Rogue level before multi-classing to Barbarian (Rogue 1/Barbarian 8/Fighter 11) can also provide some skill versatility, though the Sneak Attack feature will be largely wasted, as it is not compatible with Polearm weapons. Players straying away from the Bear Totem Barbarian portion of the build should do so with caution, as the Resistance to nearly all damage types is central to survival in the chaotic melees of Dungeons & Dragons combat, and Reckless Attack offers a reliable increase to attack accuracy.
Source: Unearthed Arcana