It's How You Wear It

I just posted all 10 fights with pelagos on my youtube playlist just watch the fights and use the strategy and you will get the achievement easily. Just click on the 10 humility fights and see what equipment I used and why. I also made it easy by adding the boss/equipment below the link. These were all done with Pelagos.

https://www.youtube.com/playlist?list=PLzpisTlcwrLzA_WnngcChDRdwIt5GVKYu

Kalisthene - Herald's footpads required to break chains
Echthra - Vial of serenity for health I recommend cheesing her assuming she hasn't been patched
Alderyn and Myn'ir - Deep echo trident so you can kick anima seed
Nuuminuuru - Phial of serenity for health as not much else really going on in this fight
Craven Corinth - Vial of Lich frost to peel him off of you
Splinterbark nightmare - Spiritforged Aegis (could really use anything) to give you an extra shield to be safe
Thran'tiok - Deep echo trident to interrupt terminal destruction
Mad Mortimer - I used ring of warding (once again could use anything) now I would using the cheese method on my playlist as you won't need to care about anything
Athanos - Vial of lich frost to keep him controlled, might be able to take vial of serenity and just face tank him for master of the path
Azaruux - Deep echo trident to interrupt infestation.

If you don't mind a bit of inefficiency, Humility Than'tiok doesn't require any equipment as Pelegos. You can just do it once for each item.

Unlocks the Following from Orluna for 1750 Anima Each:

Halo of the Discordant
Discordant Sigil of the Archon

for anyone trying this in Dragonflight:

I took close to no damage while face-tanking. Also, I basically 2 shot the boss with Pelagos.

So... Choose Pelagos. Choose equipment. Pick a boss on Humility. Walk right up to them. Spam your abilities. Tell the valkyrie dude you want to try again. Rinse and repeat. 2min per item.