Ophelia

I'd build her like a blue Lilina +Atk -Spd

She's a really powerful round 1 nuke and +Atk is a superboon. With L&D3 she would swing with 60/35, but DB3-4 or Swift Sparrow would get the job done without lowering her already poor defenses.

Build the right team for her and she can proc any special you want on the first attack, and if it was an aoe she won't need any follow-ups to finish the opponent off.

Her spd isn't fantastic to begin with. Ishtar, Linde, and even Delthea are faster with same IVs. However, her OHKO is extremely deadly and her prf helps her pre-charge a special. I recommend to accept any bane if you get +atk