Thank you !!! As much as I'm a bit frustrated not having found the answer myself, I spent around 2 hours on it lol, and my best score was leaving the Fatui guy with 1 HP ^^'. I couln't have enjoyed the rest of the game well one more day with this unsolved so I gave up and searched for thhe solution ^^'... I was so close though, I didn't think of using the Hydro character skill like this ^^'. Thanks again !
Thank you! I've tried several things, but somehow missed one step you took that I just did not see. I get too distracted thinking they want us to use all four cards and it did not make sense to me.