Depths

[Hunter Wolf]

FIVE BOSSES and no items or healing before you do aegis THEN you gotta fight a 800 hp dragon?

[Second-Hand Memes]

It takes so long!
If you're in need of tips, try to get several of the start of fight buffs from the Sealed Portal bosses as they re-apply when each boss appears.
Also, try to get 1-2 characters with team wide 1 cost buffs. These can be further augmented to add dodge, health regeneration, increased critical chance, and de-buff clear(I've seen it as an option on Erza's Guardian).