How do I design balanced encounters when one PC vastly out-performs the rest of the party?

Question

I'm having some serious balancing issues with my current campaign. Mostly due to the Barbarian. My entire party consists of the Barbarian, a Bard, and a Druid, all recently turned lvl 6. So one serious damage dealer and two supports. The Druid is circle of the moon, so not too squishy but not exactly a tank either. And the Bard is a lvl 6 Bard.

The main problem is this, I'm having trouble trying to find an encounter that can challenge the entire party including the Barbarian without the guarantee of outright killing the other two. The Barbarian has Rage, Reckless and great weapon master at his disposal which he never fails to utilize. This puts out some massive damage potential and he pretty much one shots anything with 20 or less hp.

Here's two scenarios to put things into perspective.

Scenario 1. The party still lvl 5 and without most of their gear, fights two Bulettes separately. The first one I powered down, thinking it might be a bit much. The Barbarian makes short work of it without too much help from the other two. The second one was a normal Bulette which I thought would present more of a challenge. Not so, the rest of the party had more to do this time but the Barbarian still did a good half of the damage.

Scenario 2. I decide to try throw two strong creatures at them instead of just one. Owlbears. This was definitely more of a challenge and pretty fun for me for the most part. But the Barbarian still cut the owlbears to shreds and I think he's begun to make the other party members feel a little bit useless or surplus to requirements.

Sorry about the length of the post. I hope I've made my predicament clear. Basically the tldr is that my Barbarian is completely out damaging the other two party members and i don't know how to counter that without a TPK.

Any advice is welcome. I'm totally open to good homebrew ideas.

Answer 1

Firstly, the fact that the Barbarian is out damaging the other two isn't a problem. As you noted they are support characters so they won't be doing the same damage output. The real issue is that your encounters ain't dealing enough damage out to the barbarian to make the encounters interesting. There are a few options to deal with this.

Mental effects

Barbarians are (generally) susceptible to anything that forces them to do WIS or CHA saves so you can include monsters that have effects such as casting Suggestion, Fear, etc. Blindness and spells that reduce the Barbarian's ability to hit the monster can also work. Example: I recently put my players up against Yuan-ti warriors who Suggested the Barbarian simply walk away from the fight. It removed her from the action for a couple of rounds until the caster failed the CON save and she could run back.

More monsters

You don't have to keep the types of monsters the same in the encounter so you can throw in something powerful to keep the Barbarian busy and use weaker melee or ranged monsters to give the other two something to mop up. This can also have the effect of making the combat more dynamic as more movement might result, making the encounter more interesting as a bonus. Example: Fighting a group of bandits with several archers who can reach the other party members easily but don't do enough damage to kill them (probably) but definitely give them something to think about.

More damage

Feel free to adjust the damage rolls of the monster so the Barbarian takes more damage when they get hit. Use monsters that have extra effects like causing a damage type the barbarian isn't resistant too. Example: Casters, in general or a specific example, an Eldritch Knight enemy who has the AC and HP to stand up to the Barbarian for a bit but can utilise spells to cause non-resistant damage.

I had the same issue when the group I currently play with started to get stronger. You need to play to their weaknesses and be more creative in what they come up against. But from what you described I would focus on attacks that either damage the barbarian more or direct more action towards the support PCs.

Answer 2

Create “encounters” before the actual monster encounter. Barbarians aren’t the best thinkers and should have problems disarming magical traps, discovering information on the correct way to kill a powerful enemy, coming up with the strategy for interacting with a non-enemy, or other such issues.

Answer 3

Some classes are weak to certain types of damage or enemies. For example, the shadow monk can survive after reaching zero for a turn unless radiant damage is inflicted. Another way is to put in monsters that can capitalize on the characters weaknesses. Lastly, the barbarian is bad against something that can either outlast, out speed him, or deal magic damage. Maybe a wight with a magic sword?