Night-Time Ambush

A Night-Time Ambush is a surprise fight that can appear after Camping (33% chance).

Peculiarities
The party will always be surprised by the ambush, torch level will drop to 0 although it may be increased by hero's skills (for instance Rallying Flare or Inspiring Cry), random composition of the enemy party will entail that the peril your heroes face during the ambush may vary from basically free loot to having the stress and health healing undone to a complete party wipe.

Night-Time Ambush can be prevented by use of the Camping Skills: Crusader's Zealous Vigil, Highwayman's Bandit's Sense, Hound Master's Hound Watch, Occultist's Unspeakable Commune and Vestal's Sanctuary. As with many other decisions, this is about risk and reward management: preventing the ambush safeguards the benefits of camping, while taking the chance for one to occur will allow you to spend Respite on other camping skills. Even in an ambush, the benefit of decent loot is higher as the darkness bonus provides better treasure, if you defeat it. Keep in mind the enemies encountered can be of any composition that exists within the dungeon (excluding bosses), so some ambushes are significantly more dangerous than others.

Also note that the Ambush fight counts towards the 4 battle camping buffs (e.g. Clean Guns ) meaning that after the Ambush these buffs will only be effective for 3 more battles.

Even if you retreat from the Ambush, returning to the room where it happened will make it trigger again, forcing you to either fight or backtrack to take a different path.

All in all, Ambushes are not as dangerous as they may seem, especially if your party is running some low Torch Trinkets. Despite leaving odds to RNG, it isn't too punishing to take the risk unless your party is really low on health/high on stress and you cannot afford another fight without risking losing one of your hero's lives.