It occurred to me I should crosspost this here from the other thread so that it doesn't get buried within a day or two. If you guys have any questions/feedback, fire away.
I couldn't sleep tonight so I made you guys something I hope helps. If you guys found this informative, let me know; I'm willing to make more of them for other aspects of the game. I don't know if this is the optimal strategy for this boss, but it's the one I've had the most luck with. You don't need an arena or many potions at all, but you can add them if you feel they'll help.
My accessories were:
Menacing Wings (you can actually swap these out for whatever)
Menacing Celestial Stone
Menacing Celestial Shell
Warding Ankh Shield
Menacing Worm Scarf
Menacing Frozen Shell
I would swap out the Frozen Shell with a Paladin Shield if you have one (I didn't) or that defense boosting item if you rolled a Crimson World. You could also use a third sun/moon stone which is probably the best bet. My loadout is far from optimal, honestly.