So, for those that still didn't finish Belphegor (spoiler: I forgot about the trial and just noticed today I didnt do it), Golbez does so much damage he kinda... trivializes the fight.

For the team:

Tsuki, Golbez, Sylvie, Chizuru, Vaan.

Only mandatory units here are Tsuki and Golbez. The other 3 can be replaced by kinda anyone that does similar stuff, which is:

Sylvie: Buffs demon killer for Golbez and uses her magnus mitigation turn 1.

Vaan: Breaks Oil Fire support chain.

Chizuru: LB turns 2 and 4.

For the others: Tsuki** imbues fire, uses her field and chains. Golbez uses Focus > Meteor > Osmose > Meteor

For the fight itself: Sylvie has 100% provoke, just uses mitigation turn 2 demon killer. Vaan does not uses Oil turn 1, or I would cross the 50% threshold and die turn 2 (everyone is geared glass cannon, so I had to make sure I was as close to 50% as possible but still not crossing it), instead using it turn 3. Chizuru just used katana imperil 400% ATK buff.

Turn 4 requires you to remove the ATK/MAG debuff from the party, so I wasnt even able to buff Golbez again, so everyone was at 150% killer.