
Fire trial is much easier, I think you might have disabled the other trials for testing and forgot about it because I only found fire trials in like 4 runs.
This guy got spawned outside the map by one of those boss turned regular enemy in floor 3:

Good twist by the way, it works well as a regular enemy.
I entered a boss chamber on floor 3 and it got filled to the brim with floating orbs, thankfully the virulent update plus steam is great at thinning hordes like that. Virulent update + fire trial buff also caused some fun chain reactions that cleared whole rooms.
The new boss was good. I found it easy enough to keep track of both of them and I thought it was neat how they can damage each other.
Whenever I get set on fire I usually do water + health but if I do that with the barrier upgrade I get neither water nor health and I die.
I think maybe the chem tank upgrades should be given in some other ways because they feel mandatory to get first.
It was fun to finish again.