Combination of Polearm Master and Sentinel seems very apealing for my Barbarian. >:]
With cap of 12 that combo will work only on fighter and it's extremely bad on barbarian especcially due alot of reason.
Lets hear some.
Have a bard, cast faerie fire, bless, reckless attack, ...
This feels odd ...
Advantages from Faerie Fire and Reckless Attack dont stack ... no?
[EDIT: Sorry, written at the same time as the previous post] Faerie Fire and bless also shouldn't be castable by the same character since they requie concentatrion (at least in the core rules, don't know what's the current situation in BG3.
Regarding Barbarian:
I'm also not sure what would be bad about a barbarian with polearm master and sentinel at level 12? You should have easily STR18 by the end. That +5% to hit from ST20 means little. Personally I've made good experience with even an unoptimized elven wild magic barbarian with ST16 and polearm master - I'm waiting for the chance to add sentinel to him. I would though consider taking great weapon master instead of sentinel if you have ST 18 on him, but that's personal preference and if you see him as a hitter or protector.
For me polearm master is actually far more interesting than sentinel, since you can with simple positioning provoke the opportunity attacks when you force enemies to move towards you. You initiate the fight at 10ft, move a step back after your attacks (most likely out of the range for an enemy opportunity attack) and wait for him to move up - now sentiel would turn this very nasty since a hit would make the enemy stop right there. For me a very interesting build with a barbarian's bonus damage from rage. By the way the only downside being rage using up the first rounds bonus action instead of the additional attack, but that's really just a minor thing IMHO. A fighter's 3 multi attack at level 12 for me also doesn't outweight the barbarian's additional class features and damage reductions. I think fighters and barbarians are not that far appart at level 12, even though fighters could go nuts and make 7 attacks at that level with polearm master, but until then I wouldn't say a fighter is better than a barbarian and even then I guess its more to it than the 7 attacks mathematical damage.
