Ran mostly Garden of (Sent/Gun) 5-6 as not all characters were max.
Grim Reaper - Fury can doom whole team
Undead Rescuer Assassin - Only single with power
Alchemist - Power can do multiple
Troll Assassin - Passive is accuracy up
Manual is easiest but slowest and you can usually get 5-10 per run, sometimes more, but sometimes less.
Grim Reaper should be 70% (maybe 75%) with accuracy up, but I've got 0/5 before, so RNG issues as usual.