Yosef is Decaying Winter's final boss, arriving on the tenth and final night. The collected guides confirm his role as the climax of a run, but only a few details are documented — below is what is verified versus what is 待确认.
Confirmed from the guides
When Yosef spawns on wave 10, the agent device announces "Heavily armoured hostile detected." That line is the in-game signal that the final boss has entered the fight, making him distinct from the wave enemies you face earlier.
What is 待确认
Exact health, attack patterns, arena, and rewards are not covered in the beginner or field guides we gathered. Treat any specific numbers from other sites as 待确认 until the official Discord or Trello confirms them.
Preparing for wave 10
Surviving the final night means entering with full rations, a strong frontline perk, and coordinated team play. The beginner guide stresses sticking together and using defensive traits like Dependable or Fearless for the boss push.
Verify before the run
Since the core guides skip Yosef's stat block, confirm details through the official Discord and Fandom wiki as the game updates. Do not plan a strategy around numbers you cannot verify.