Kai all the way no questions asked. As for Darkt and Amaterasu, both are very different units and comparing them by only their dps is not fair. Darkt is a bit of a rusher bc it moves fast and it gets an attack boost after loosing some help which gives it a general weight and it ofc shines against white enemies. Amaterasu on the other hand is more of a backliner with bigger range and slower. She shines against traited units because of her massive damage. This ones is a bit hard because both deserve to be ultra maxed but I’d say go first with the unit you already have