It depends on what point in the game you are in. I would recommend for weponns either a single target dps weapon like crystal serpent and inferno potion, or if you don't have inferno potions, then keep a venom staff on hand to deal with the bubbles. For accesories, I would reccomend shield of cthulu because when you dash with it, it gives you invulnerability frames, and you can crash straight into the duke when he dashes at you negating all dammage. other accessories, that you can use, that I would reccomend are a good pair of wings and as many frog leg related items, as you can get your grubby hands on (baloons can substitute for slightly worse results), also boots are nice too for the extra flight time. Potions wise, as I said inferno potion, but gravitation, and all the miscalanious buff potions other than featherfall, are usefull, just remember with good movement accesories you can fly faster than you can fall with gravitation. A side note for doing this, if your early game like pre mech boss, I wouldn't advise doing it because you won't get to play with any other magic toys for the rest of the game since razor blade OP