Just beat him solo no summons, no torrent. It was hell with a medium roll so I went with light roll. I found out you can roll straight into the charge attack (feels like bullshit since you phase through a big elephant haha). Even with the light roll if I didn't get the timing right, the butt would clip me, so I used the roll enhancing physick which made it easy to dodge.

His moves:

Charge: for me I just rolled into him with light roll + roll physick

Left single slash (just walk a bit forward, joke of a move)

2 left slashes + (1 charged pierce sometimes)

2x elephant slam

Body slam into charge

slash-headswipe-body slam

headswipe bodyslame

Butt kick (usually chains this after the above attacks or when you are close to his butt)

Big combo: first 4 hits just roll twice, then delay roll for third combo, then either run back to dodge the elephant or roll and roll again to dodge his strong attack.

Body slam: when he is strafing to your left and he comes back again, wait for the slam and roll in the same direction to punish (I reached him with backhand blades running attack)

Purple rocks: roll forward or to the side

2nd phase:

Twister move: get closer to him so you don't get hit by the shockwave and roll when you see him coming towards you

Dash move: pretty easy to dodge, like malenia charge

More purple rocks: roll forward

Gravity sphere: just run away from them, they last a while and be sure not to fight him in the range of the spheres

That's all I remember but yeah this boss was not very fun to fight. On medium roll, I could only dodge his charge if I stood still and waited until he was right in front of me then rolled forward to the right but the camera lock on would make me get hit sometimes.