Thanks for even more feedback! Once again, everything's on point and will definitely help me make the game better!
Reward icons - I do rely on the player to memorize some of it, but I agree hints won't hurt. I might have to rethink my approach on Attunement conditions, too: the idea initially was to require certain trinket for Attunement to be offered. This part might change, and I'll definitely keep an eye on this one in further playtests.
What you experienced with monsters suddenly dying could be a different room objective - in some rooms, you have to survive for the duration. In those rooms mosters tend to spawn outside the screen and walk into the arena. Also, there is a small widget at the edge of the screen telling you to either defeat several monster squads or survive. Thanks for bringing it up, I kinda forgot about this thing not being explained properly, it's just a tiny widget in the corner that is probably very hard to notice.