Alright, so I’m thinking I’m going to make Mercedes my next non-Grail project, since I recently acquired a 5* +SPD copy of her.
Right now, I’m looking at something like this:
Meloncholy/Witchy Wand (need fodder)
Joyous Staff (need fodder)
Close Counter (for fighting Dragons)
Any Solo/Bond/Push skill in any combination of ATK, SPD, and RES.
Wings of Mercy
Wrathful Staff (Fodder)
Mercedes has a fair amount of flexibility to her, though not as much as others, 'm just not sure what I should go for as a standard build until I can specialize her for other modes.