Take the Mobile feat
Your goal should be to get into melee, apply your ancestors to the boss, and get away. With the Mobile feat (PHB, p. 168), you won't provoke opportunity attacks from enemies you attack, and you'll have extra movement (in addition to a barbarian's own extra movement) to leave range. If at least one of your allies stays near the enemy, the enemy has a tough decision to make: eat an opportunity attack (or three) or attack your now very tanky allies.
In practice
One of my current Adventurers League characters is an Ancestral Guardian / Battle Master using this strategy. When I originally wrote this answer, he was an Ancestral Guardian 6 / Fighter 2. Since then, he has capped out at Ancestral Guardian 16 / Battle Master 4.
Throughout all tiers of play, he has been extremely effective at preventing damage on myself and my allies. Why be a Bear Totem barbarian when your ancestors turn your whole party into Bear Totem barbarians! As far as encounters and magic items go, AL tends to have 3-4 encounters per module, and my character only had a +1 weapon for levels 5-7 without feeling weak.
Other considerations
- You mention that the Champion fighter in your group is cowardly. The nice thing about this build is that (unlike the Cavalier from Xanathar's) you can...encourage...allies to synergize with you without forcing them. Fighter not tanking? Apply your ancestors and use your 50' of movement to run past your cowardly ally. The enemy will likely engage with the fighter since it can't reach you. When it misses the fighter, play up how your ancestors distracted the enemy. Your allies will learn that ancestors equal safety.
- It's usually better to apply your ancestors to the least damaged enemy first and then leave them so you can attack the most damaged enemy with the rest of your party. Your ancestors do nothing if the enemy is dead.
- If an enemy is highly mobile and dangerous, you can stand back and apply your ancestors from 150' away with a longbow.
- If you also multiclass into fighter, the Battle Master's Menacing and Goading Strikes (PHB, p. 73-74) are like a mini ancestors effect. They synergize well with the rest of the build.
- As @Ben Barden pointed out, the Sentinel feat on the fighter (PHB, p. 169-170) in your party would assist with this playstyle by preventing even mobile enemies like dragons from leaving to hit you.
- I would not recommend taking any feat or other feature that uses your reaction. At Level 6, you get Spirit Shield, which prevents an average of 7 damage per round as a reaction. That's similar to casting healing word every round without using resources! With the hit and run playstyle, you often won't be next to enemies to use an opportunity attack, so you can (and should) use Spirit Shield every round.
Bonus math
This build always feels strong in play, but I was wondering how strong it actually is.
TL;DR: the wizard, protected by ancestors, survives longer than the reckless-attacking barbarian.
The PCs
Class |
AC |
Con |
HP |
Ancestral Guardian 5 |
19 |
+3 |
55 |
Champion Fighter 5 |
20 |
+3 |
49 |
Hunter Ranger 3 / Rogue 2 |
16 |
+2 |
42 |
Evocation Wizard 5 |
15 |
+1 |
27 |
Archfey Warlock 5 |
14 |
+2 |
38 |
Since this question focuses on survivability, I am assuming that the barbarian is using a one-handed weapon and a shield. If not, a hit-and-run playstyle becomes even better. (I would recommend a two-handed weapon to anyone trying this build.)
The monsters
This fight will be a Deadly encounter, as it is the boss fight. The PCs will face:
- One CR 5 Gladiator (MM, p. 346)
- Five CR 1 Duergar (MM, p. 122)
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 ancestors
I will assume that the barbarian's ancestors are applied to the Gladiator every round. (There is a small chance that they will miss both attacks, even if they attack recklessly for advantage.) For anyone but the barbarian, the ancestors impose disadvantage on the Gladiator's attacks and will provide resistance against any damage the Gladiator may do.
The numbers
As a baseline, the barbarian will last 4.4 rounds against the Gladiator while attacking recklessly, or 6.9 rounds normally. The barbarian numbers assume that they have resistance to the attacker's damage. If the party faced a CR 5 Fire Elemental instead of the Gladiator, the barbarian no longer has resistance, but their ancestors still protect the party against all attack damage.
Class |
Base Rounds |
Ancestors |
|
Ancestral Guardian 5 |
4.4 |
— |
Reckless |
Champion Fighter 5 |
3.4 |
18.4 |
|
Hunter Ranger 3 / Rogue 2 |
2.0 |
7.0 |
|
Evocation Wizard 5 |
1.2 |
3.9 |
No shield |
Archfey Warlock 5 |
1.6 |
4.7 |
|
The wizard can last around 5 rounds protected by ancestors if they cast shield on the first two turns of the fight. If the barbarian took the Tough feat (gaining +2HP per level) instead of Mobile, they would last 5.2 rounds recklessly, or 8.2 rounds normally. These are still a far cry from the 18.4 rounds the fighter would survive.
The conclusion
The fighter becomes a truly incredible tank, surviving more than 5 times longer than without the ancestors. In fact, every PC survives longer than a barbarian who is attacking recklessly (all while allowing the barbarian to do so without penalty by keeping out of range). Who knows, you might even make a brave warrior out of your cowardly fighter ally!
Its viability depends on external factors
It is mostly viable, actually the only viable ranged Barbarian build in my opinion1.
The external factors are:
- party composition
- available space
- encounter type (if it is a single boss, or many smaller monsters)
- enemy type (if it uses attacks)
When I played this build, it was quite useful when everything was optimal.
However, its usability decreased significantly with one of these factors missing.
Party composition
As mentioned in the comments of this answer, this tactic is only good if your party members can keep the target of your Ancestral Protectors (Target) away from you.
Either they have to physically hinder its movement, or discourage it with threats of Opportunity Attacks.
You will want to have at least half of the party members to be in melee.
When the Shield Master fighter was not present at our encounters, my Barbarian worked a lot worse.
Available space
If you fight in a dungeon, sometimes you just can't get far enough from the target while maintaining line of sight.
Encounter type
If there are lots of enemies, you might get far enough away from the Target, but his comrades still might be adjacent to you, causing disadvantage on your attacks. You have to hit your target to trigger Ancestral Protectors, so this can be a big problem for you.
Enemy type
If the enemy does not use attacks, only breath weapons or spells, Ancestral Protectors become irrelevant. Unfortunately the resistance is only against his attacks.
Conclusion
It is not viable for dungeon crawling with a party of 4 Sorcerers, but with the average party in the average encounter you will do more than fine.
Recommendation
Use a Hand Crossbow instead of a Longbow and multiclass to Rogue instead of Fighter.
Hand Crossbow
With the Crossbow Expert feat you can attack without disadvantage even if you are adjacent to enemies, negating the worst consequences of a tight space and many smaller enemies.
When you already have the feat, Hand Crossbows give you the most DPR .
Rogue
2 levels of Rogue make Disengage a bonus action, very valuable in tight spots.
Also a Rogue Multiclass provides better DPR increase than a Fighter2, and this area is where you are very much behind a usual Barbarian, as you can't use Reckless Attack and the damage increase during the rage.
1 Being at range gives you extra survivability, by making it harder for others to target and hit you. Ranged characters come away from most fights undamaged in experience, so resistance is mostly wasted on them, and no other significant Barbarian features are usable at range. Other ranged Barbarian's usefullness in combat is below that of a Ranger, and they are famously weak.
2 A single level of Fighter might still be a good idea for Archery fighting style.
Best Answer
Fighter 5/barbarian 2
One attack with Advantage is worse than two without, unless you have Sneak Attack*.
Damage comparison
In both cases, you roll 2d20:
As you can see, Advantage is identical in some cases, clearly worse in others, but never better.
Reckless Attack is not free
Providing Advantage yourself is quite a steep price
Other sources of Advantage exist
If your enemy is prone, restrained or provides Advantage for any other reason, your two attacks just got that much better. In the other case you DPR does not improve, you just don't provide Advantage.
tl;dr: Even if a 2nd level barbarian always had Advantage and without a cost, Fighter 5 would still have better DPR than Fighter 3/Barbarian 2
*If one of your allies is standing next to the target, two attacks are better than Advantage on one, even if you have Sneak Attack