Death's Gambit: Heroic Endless Boss Fight

Most people say HeroicEndless is the hardest boss in the game but I personally found Heroic Amulvaro much harder. Each phase of Endless has a pattern you can learn, just don't forget about the modifiers.

[@thomasmcaleer6667]

I defeated her on Heroic but didn’t get the Fallen Angle’s Thesis

[@thomasmcaleer6667]

Has anyone got the same issue with not getting this?

[@Shpoonman]

I'm on this fight right now, any tips/build strat? I'm 150 strength build w/ 100 in Strength, 40 END, and 20 VIT using Vados +10 and the swarm gun

[@ObsceneSociopath]

That's more or less the exact build I used in that video. Obviously a +10 weapon is desirable and I believe all my armour was on +7 (Chest may have been +8) & my Swarm although I hardly used it was +6.
The only things I can suggest really are use the Turtle Shield so you can block from any direction and if you have the have the Perfect Block talent, you'll be able to block her entire combos once you get the timing down. Also, depending on how many Leaves of Gaia you have collected or have left, augment as many of your feathers as you can, I personally augmented all feathers as I had 11 LoG & hadn't used any of them, I would suggest backing up your save though if you take the Leaf route as any you use are lost when you die & cannot be replaced.
You will also need to pay close attention to the curse as it changes each phase, in the video I had to emergency switch to a different phase from the pattern I'd learnt as I needed to block an attack other I'd have taken 1000 damage & the usual route I took would have left me with nothing to block. If I remember correctly, Sadness, Rage & then Fear is a good order to run phase 2-4 as the curses have the least impact on you in that order based on how you need to fight.
Other than that, a lot of it is just learning the attack pattern in each phase. Phase 5 could be considered the hardest as although the curse is less of an issue, in that Phase Endless has access to all of her attacks from the previous 4 phases making her harder to predict.
If you've already beaten Amulvaro, you've already got this in the bag, he is a much harder boss, just a little patience & practice & you'll be over the final hurdle. Amulvaro literally took me about 3 hours to beat but I took Endless down within 20 minutes, my 6th attempt I believe as she is far less RNG based.
Good luck.