Hi! The art and story so far look incredible!
For some of them, the distance between the text and the border of the text box seems inconsistent.
Also, I'm not sure if this is the kind of feedback you want, but if I may make some suggestions, in this sentence:
That technique consisted on accelerating the absortion of the spiritual energy of other living beings, and assimilate it to his own.
That technique consisted of accelerating the absorption of the spiritual energy of other living beings, and assimilate it to his own.
And in the following ones:
imortality → immortality
sworn → swore
Though, I think this is just me being nit-picky.