I'd be tempted to try something like:
Boragar: leader and starting off with increase res/speed (try to have your champions at 80 res or more before Boragar's aura, should let you resist dreadbombs). You should also try something like Champfort and his decrease accuracy A2 to get this done, but that is subject to weak hits.
Stag Knight: Speed down A1 and dec att/dec def a2 which will be extremely useful here
Doompriest as either your fastest or second fastest champ, giving us passive heals
then I think I'd look for DPS. Yakarl might make sense because we can freeze the bombs, then perhaps something like Rhazin or Yannica for pure damage. I'd suggest Drexthar but with Stag and Boragar we should be taking a lot of turns. For similar reasons to Yakarl, you could also try Ninja. But I think the first thing is trying to bring down how much damage Bommal does through preventing bombs and hitting him with attack down.
If we end up needing more sustain, we can also try Scyl to replace one of the DPS to get those passive heals on top of Doompriest's.
edit: you can try Scyl over Doompriest to start, just because the heals will be a bit bigger. Especially if she's built well enough to get through taking more damage due to bad affinity