Corridor length does not affect 'how far away' a room is, only a count of rooms themselves between your room and the boss room.

If both rooms are on the same height, it's the one further on the right. If two rooms are the same length away, it's the room furthest down.

When locating a boss, it is almost always the room farthest away from the entrance room.

at 50% progression to unlock apprentice Hag, a medium mission will unlock the boss AND progress to unlocking the apprentice Brigand Pounder by 25%)

Excess unlock progression from expeditions which unlock the boss DO appear to carry over to the next boss.

*(source: ingame observation from July 8th, 2018, Bloodmoon difficulty).

For Champion bosses, successful short expeditions will increase the unlocking progress by 25%, medium by 30%, long by *40%.For Veteran bosses, successful short expeditions will increase the unlocking progress by 33%, medium by 50%, long by 67%.For Apprentice bosses, successful short expeditions will increase the unlocking progress by 50%, medium by 75%, long by 100%.The longer the expedition, the more progress is made towards unlocking the boss. Unlocking bosses requires successful expeditions in the relevant location. They invite you to join them at the Courtyard. It lurks within shallow waters of the Moor… There are only two Mini-Bosses in the base game (the Shambler and Collector) with two others being added with each DLC: Crimson Court DLC introduced the Fanatic and Color of Madness DLC the Thing From The Stars.

Mini-Bosses are encountered roaming in the hallways of any mission. Bosses are only encountered in missions that require you to slay the boss. There are two types of bosses: Bosses and Mini-bosses.

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