Finally did it, If you wanna know my loadout then comment, I'm not gonna post unless needed. Down below is an explanation on how I glitched the final boss room to stop spawning enemies.
Final Boss Room Ad Cheese:
I don't know what for sure stops ads from spawning, but it seems when I shoot witherhoard at the door, bank to bring the Centurions out and immediately killing them stops the door from closing for some reason. Or Solar burning affects the door. Haven't figured out but just look at what I do at 45:27
Timestamps:
0:00 Entrance
5:04 Nightmare of Gahlran, Sorrow Bearer
18:38 Jumping Puzzle/Statues
25:07 Unlocking The Vault
38:39 Jumping Puzzle 2
43:29 Nightmare of Caiatl, Princess-Imperial