Hmmm. I think Batman might need the hellbat, but he’s also personally taken down darkseid, the justice league, and other supernatural threats so I’m not sure. If he does use the hell bat, I think he should also keep a little piece of the god-killer sword inside the hellbat to create like a god-killer knife, which could combat various spells doctor strange casts and also that one mystic sword he uses. (sorry, I can’t remember what it’s called) Batman’s acrobatics could also be useful when avoiding magic blasts other spells. If he’s sent through any portals, he could use zeta technology (which he could build into his suit, as well) to teleport back to Strange. To beat Doctor Strange, I think all Batman has to do is get close enough to pummel him. I think Batman’s training beats Doctor Strange’s art of Kamar-Taj. But anyways, there’s my answer. :)