Entropy 15

• Wave 1 (Boss Wave)
  Flan Medley and Two (2) Small Flan Medleys.
  Starts with Thunder and Wind Resist. Flan Medly opens with Split then spawns small flans with the same resistances. The adds only do BRV/HP attacks. Keep them broken and you’re fine. Flan Medly uses Generate Body once adds are killed which is around 40k BRV Gain and gains BRV Damage Reduction. If you break the Flan Medly after it uses Generate Body, it will do High Split which re-summon the adds, raises its own ATK/mBRV and grants itself BRV regen buff. If you don’t manage to break it, it will perform an HP attack (BRV+HP, can be ST or AoE) and change to Ice Resist Stance and stick with Generate Body.
  

Strategy is to keep the adds broken so you don’t get HP Attacked. Prepare to BRV shave the Flan Medly when the adds are killed; instant break removes the problem entirely (ie. Trey & Gabranth). High Turn Rate/Speed down/Turn Manipulation can get you enough breathing room (ie. Noctis & Machina). Tanking the hit and breaking after also works (ie. Basch, Nine).

• Wave 2 (Final Boss Wave)
  Spineclad & Countsteam.
  You want to kill Count Steam first because it enrages, removing all debuffs on it, and ramping up the BRV Damage Reduction significantly. This boss gets to be very fast. It has hard hitting attacks - Multislash (BRV+HP) and Steam Burst (AoE BRV+AoE HP) which can one shot you. Avoid being broken.
  
  Spineclad has a 3-4 turn cycle which includes hard hitting BRV attacks and charges at the end of the cycle. Charging grants itself multiple buffs and follows up with Spear Ray (9-Hit BRV+AoE HP Attack) that can wipe your team. Debuffs help mitigate the damage from this attack and framed ones help prevent all the buffs of Spineclad from applying. You want to heal immediately after this AoE attack. Having a tank mitigates the danger for both these bosses.
  Debuffs Inflicted: ATK/iBRV/SPD Down, Poison