Beelzebub

What makes the sky blue?

Triggers 100% - 51%

Massive DMG to all allies

30 hits to cancel the omen. If cannot cancel, tank with Fediel 1 to not get stunned.

200% DMG to 3 allies.
Bubz becomes OD and normal omen changes, so cancel this

Deal 10m DMG to cancel, its really easy to deal 10m DMG.

100% DMG to all allies. Inflict Summonless

Doesn't hurt, just tank it.

Bubz goes to a "standby mode" for 4 turns.
Gains 5 buffs that basically makes him take 0 DMG and also reflects DMG

Dispel all 5 buffs.
Deal 5m DMG to cancel.
Make sure you have 1 dispel, with 5 people in the raid, thats 5 dispels already.

24 hits to random allies. 1 turn cut to all buffs duration for each hit

Deal 15m DMG to cancel, its really easy to deal 15m DMG.

300% DMG to all allies. Inflict Defenseless and Bore

Land 6 debuffs to cancel. Fediel 2 is 3 debuff, so just Fediel 2 and auto attack.

2000% DMG to all allies

Deal 20m DMG to cancel, its really easy to deal 20m DMG.

No OD trigger?

If you cancel all 10m/15m DMG omens, then OD will never appear

You want to bring a character that can apply debuffs (E.g. Lich, etc.), and provide some survivability (E.g. Fediel, Lich, etc.).

For reference, a common setup would be Kengo, Fediel, Flex, Lich, Flex, Flex.