Ruin Explorer
Legend
There's not much else it could be other than your party comp, given you're level 12. I am anything but a tactical genius. I may even be a tactical idiot. So I doubt it's a skill issue in the normal sense.
Party comp issue.
Really serious one too. You're choosing to take a character who basically losing an entire round when combat often doesn't go beyond 3-4 rounds, because the rest of the party can't support him to get Advantage/flanking. That's the definition of a party comp issue.
Further, it stays a bad issue, because even with Advantage/flanking, he can basically at best kill one enemy, and as you've correctly explained, most fights feature a lot of enemies. So why are you bring a class/subclass that can, best case, blow up one enemy per round? Thief has incredible synergies because of the two bonus actions, but by being single-classed you can't take advantage of any of them.
Funny how that never happens to Gale. I think positioning plus him having good layered defences is pretty key to that (plus stuff like Bless and I think an item giving him Advantage on CON saves). Have you considered you might not have enough defenses on your main character?
But part of it is again a party comp issue. You have Shadowheart. She's a Cleric, so she can't cast Haste and use her higher AC to protect it. She can't cast Confusion or indeed many AOE CC spells. Indeed her concentration spell options are pretty questionable. Also Clerics aren't good at killing people. Clerics kind of blow, especially at endgame. Sorry Clerics.
You know this, so why are you bring the lowest-damage Rogue subclass on a single-class Rogue, the class least able to deal with "a stupid amount of enemies"? Why are you bringing a single-class Cleric, who is also pretty bad in that situation? Does your Sorlock at least have some really mean AOE damage spells and CC?
(Also, how are losing concentration that easily with a Sorlock? Sorcerers have CON saving throw proficiency. You might want to respec and make your level 1 class Sorcerer so you get that, if Warlock is your level 1 class. In practice, as a caster using concentration spells, CON is a much better saving throw to be proficient in than WIS.)
