So yeah, about day 3 challenge... I tried using Sucrose Swirl-EC team. I thought I was being clever here. You see, the Kenki fight had more than one enemy so that should be good for triggering chain reactions. To add to that, all those ATK% and Crit debuffs shouldn't even matter since transformative reactions only care about EM and character level. My newly lvl. 90 Sucrose had >800 EM. "It's perfect." "I'm a genius", I thought. I probably could get 7000+ score too from this cheeky attempt. Imagine.
Turned out bringing Xingqiu for EC was a mistake. Xingqiu's ability = Wet. Wet + Cyro field from one of the Kenki = Frozen disaster.
Switched immediately to more traditional team (Keqing, Fischl, Bennett, Zhongli team), lowered some debuff options, got my 5000ish score and then get out lol.