The boss throws a bomb that later detonates much like the prophet boss fight. All of them are human so +human bonuses will help here, and all try to inflict bleed in some way (apart from stress dealers) so bleed resist helps too. All enemies are variations of the bandits usually fought in the Weald, starting off with weaker ones building up to the strongest. You do not get the chance to camp so bringing a stress healer can help and using food to heal up before the last fight may be necessary. The mission itself is a small fixed map, bring as many supplies as possible: torches, shovels, food and especially bandages. Doing so will stave off the event and you will get more chances, but importantly won't incur the penalty for ignoring the event (destroys some upgrades in town) This mission is darkest difficulty meaning if you retreat a hero is guaranteed to die.

If you are unprepared when it pops up I suggest sending a team of fresh recruits in to die horribly.

This is for beating the boss of the town event 'Wolves at the door' which can spring up after having more than three heroes at resolve level 5.

Wolves at the door darkest dungeon map