I come humble - desperate - and flat out asking for help

[madskillzO25]

It's been around 6 months and I can't beat the Lothric Prince next to the Archives in DS3.

Is there a way I can go back and summon something to come aid me in this fight? How do I beat it?

I have upgraded my weapon as best I can, use lightning, and my overall character is at 120. I need help.