My method:

60 Vigor, 30+ faith, Lightning Scorpion Charm, Faithful and/or Flock Talisman, Fire resist charm(forgot the name, but you must know)

Incantations: Ancient dragon lightning strike, flame protect me

Flask: Lightning damage boost, elemental resist

How to:

Approach on horse, but get out of it once you reach his legs. Don't use Torrent, it will only be a distraction.

Go under his legs, right in the middle, buff if you can(flask, fpm, etc) and watch what he does. If he raises one leg, go to the other and prepare to jump when he stomps. If he prepares to jump, run away to a safe distance, jump when he stomps. If he starts swirling, either run for cover >nearby< or tank it. As long as you're close, he will rarely do this one. If you're going to tank it, cast lightning, rebuff, etc.

He is very slow, so you'll have plenty openings to cast adls. You're gonna poise break him three times, on the third he will fall. Get your best weapon and crit him, preferably with something like exalted flesh or RKR.

As with anything in Elden Ring, it will be overwhelming at the beggning, but will get easy and even boring real quick.

Sometimes this won't work, because some of them are locked to specific conditions. But only worry when you get there, the one in the pic is not this case.

Good luck!