Beating the True Conqueror (Rank 8) which is unlocked by completing all quests in the game and getting Dream's Edge to unlock him.
4 Physical Unions - Trident Formation 1 Mystic Union - Pentacle Formation (With Cachexia)
Use Cachexia to eliminate his EoT attacks entirely.
The fight went well enough for my very first try, though poor Duke of Ghor's union took the brunt of his attacks, haha. If his union was not so weakened, we would have seen Duke pull out his powerful Weapon Art on the boss, but at least Jager saved the day with his instead. ^_^
My PS4 Profile: https://psnprofiles.com/LiveAndLetEDO_SG
THE LAST REMNANT Remastered https://store.playstation.com/#!/en-sg/tid=CUSA11588_00
Appears on these pages
Notes If At Hatred's End was not completed, he will not use Abyssal Gate in his normal...