I have the impression that the enemies will gain increased damage when you kill nearby enemies. As such, if you leave certain enemies alive for too long whilst constantly killing everyone around them, they’ll keep gaining damage until they just one-shot you. Thus, the mode will mainly require coordination in regards to target prioritization.
As much as I like these challenge modes, I wish the description was better. First of all, they don’t tell you that any of these modes are on expert in the mini description below the name. And they’re also very vague about what the mode entails.
Also while I can’t 100% confirm this, the “Nearby enemies are enraged” effect seems to need LoS to function. If you can isolate an enemy via Ice Wall or Boop/Hooking them round a corner and then killing them nobody else gets the bonus.
Yeah, they really could do a better job at conveying information. Way too many people enter those challenges expecting to encounter normal or hard difficulty bots (at least in the first week).