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, and the torch level will drop to 0, although it may be increased by hero's skills (for instance, Arbalest's Rallying Flare or Crusader's Inspiring Cry). A 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. Retreating from an ambush fight is impossible.

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 duration of camping buffs (e.g. Highwayman's Clean Guns), meaning that after the ambush these buffs will only be effective for 3 more battles instead of 4.

Nighttime ambushes do not occur in the Darkest Dungeon or in the Farmstead. This allows stronger battle skills to be used instead of ambush protection skills.

Preventing Night-Time Ambush
Nighttime ambushes can be prevented by use of the Camping Skills:
 * Crusader's Zealous Vigil;
 * Highwayman's Bandit's Sense;
 * Houndmaster's Hound Watch;
 * Occultist's Unspeakable Commune;
 * Vestal's Sanctuary.

If you don't have camping skills which prevent the ambush, it's wise to shuffle your heroes before camping: so if you get ambushed, there will be a chance that your surprised heroes will reshuffle themselves in their right positions. Another option is to equip combat skills which can be used to reposition the shuffled heroes (such as Hellion's Breakthrough) or are usable in suboptimal positions (such as Grave Robber's Pick to the Face).

The Crimson Court DLC
The Courtyard area has unique torch settings which persist even if you get ambushed after camping (despite the visual effect of darkness). It means that monsters will not receive the usual increase in their damage, accuracy, and critical hit chance, while your heroes will not suffer from more stress than usual.

The Shieldbreaker DLC
When camping with the Shieldbreaker, there's 50% chance to encounter a special flashback fight which overrides the normal ambush and cannot be prevented with camping skills. The Shieldbreaker will warn the player with a special bark that happens after the player selects the amount of food for the party to eat, and in this case you are free to spend all your respite points on preparing for the flashback fight instead of trying to prevent an ambush. However, if the flashback warning doesn't appear, a standard nighttime ambush can happen as usual.