I didn't realise Minthara was a possible party member. I was busy killing all of the goblins and she was hanging out with two of them, so I snuck up on her and attacked her before she could say anything.
Warlocks are just regular mages really. They only get two spell slots of their highest spell level, but they get them back after every short rest, so you should be able to use both in every fight. They can also get some extra spells to use once every long rest from their subclass and/or Invocations. Other than that they just have a very powerful cantrip in Eldritch Blast for when the fight takes more than 2 turns (or you have the Repelling Blast invocation and see an enemy near a cliff/drop).
I didn't know you could break your oath in Baldur's Gate 3, that does seem annoying.
I didn't know anything about eldritch blast. The rest of his spell lineup seems unimpressive, but if he has a great cantrip, then that makes up for everything as long as you don't get bored doing the same thing over and over again. Also, I'm guessing all the big guys of Act 3 probably shrug off Eldritch Blast. But they shrug off everyone else's spells too, so that's not a knock against Warlock. The big thing is that if eldritch blast is all you can do in a turn. At the highest level it does 4d10? plus attribute bonuses, so if that was the only attack you were allowed in a turn and you did about 26 damage, that would be one very long fight. He'd be better off buffing a damage dealer or debuffing the bad guys. Lea'zel and my monk can do well over 100 damage per turn now, and the sorcerer, while not nearly as much of a single target damage dealer, can do crowd control and a lot of utility spells. I give Shadowheart credit for all the people she can summon, so she can do decent single target damage and also crowd control, and she can heal.
Druid, though, is probably better than Cleric for healing because of being able to call a water elemental, which can heal someone every round. He can also call the woodland creature, then slip into dinosaur form and eliminate armor, which is incredibly helpful
Damn, I don't even remember what I'm posting about. Think I'll stop and have a bite to eat.
Oh, and we beat the game. That last battle is something else. That's why my brain is fried.