Hall of Trials Archdemon Mercedes 5 Alternative 2 - SS+ Grade - Being Attacked? Fight Back!
Well, it's true that as long as she doesn't have buff, it's easy to defeat her. But if you can't, just don't give up. You still have a chance to win.
Tips :
Always know the advantage and disadvantage first ( for all of hall of trials )
The most known of Archdemon Mercedes ( in hall of trials ) : make sure that she isn't buffed, then it is easy to defeat her.
Don't have any buff if you can. If not, then make sure that the buff won't haunt you when the minion steals it. Especially barrier and invicibility buff.
About debuff cleansing, it's better to do it without applying buff in the same time. You can use Elena, Kizuna Al, Ray, Wondrous Potion Vial, Jecht, etc. for that.
If your damage is not enough because there is a soul weaver in the team, then replace him by a ranger equipped by bloodstone artifact.