Diminutive swarms impossible to beat

[Warboss Tuska Daemon-Killa]

Looked up what to do, suggestions were elemental weapons, call lightning, area attacks with alchemist. I'm grey ♥♥♥♥♥♥♥ tower in act 1 and I can't beat the 3 swarms summoned by whats-her-name in the dining hall. I have tried the fight 10 times now and I'm ready to uninstall (for the second time).
1. Don't have an alchemist.
2. Call lightning doesn't work on diminutive swarms. Tried it.
3. Only Ember has burning hands and it does 6 damage most of the time, at best 12 or so. Three swarms with 25hp each and they deal like 26 damage a turn.
4. Woljiff has the burning shortsword. Everyone dies before he can kill the swarms.
5. Even with Grease in the doorway and grasping vines slowing everyone in the room, there isn't enough time to deal with the 10 enemies and the swarms.
I am on Core btw.

[ChompyRiley]

*shakes walking stick in fury* You young whippersnappers don't know how good you got it! In my day to buy a game we had to go to a real honest-to-god physical store! Ten miles, up hill both ways, AND it was snowing!

[Destroyner]

Using the doorway as a chokepoint was a smart move and is still a good strategy, just not on this fight. I see you've already beaten it so I won't say anything else about it. All I will say is that if you have the DLC companion Ulbrig, I would strongly suggest to either take him with you or unequip his necklace and keep it available for one of your other characters. I don't usually bring him outside of his quests. You will be fighting more swarms soon that aren't summoned so they have to be killed and his necklace is the biggest power boost against them. As the game progresses, you will get multiple copies of it to put on several party members.

Deo's advice was good aside from the difficulty suggestion. It is his go to for some reason and I would just ignore it. The nice difference from playing tabletop is the ability to try a fight multiple times and change your strategy. If I try a fight a couple of times with the same strategy and it is just not working, I like to reload and take a minute to think about what specifically went wrong and what changes I could make to my attack plan to alter the outcome. It can be easy to get tunnel vision and just try repeatedly with the same strategy, but a lot of this game is knowing what works for each fight.