It's kind of hilarious to just no-sell just about everything the boss can do, if you are able to build towards directing almost all single target attacks towards a super effective tank.
Formation used:
- Imperial Arrow (increased targeting chance for party member in front along with auto-defending after using actions, decreased chance of being targeted for all other party members in back, additional increased speed for the whole party)
Abilities used for Emperor specifically, as the rest aren't as important for this demonstration:
- Auto-Parry (50% parry chance with sword equipped)
- Perennial Victim (increased chance of being targeted)
- Tough Hide (20% chance of completely nullifying incoming damage)
- Giant Killer (honestly filler, if you want super ultra tank, there is one other passive that lets you survive an attack at 1 HP if you had 30% or more HP beforehand, but I didn't bother grinding for it)