Anything with good range or DoT. Don't get in close unless necessary. I also recommend swapping between Ichor straight to Crystal and/or Chlorophyte Bullets and back again once the Ichor wears off(If in a crimson world), or the same tactic with Cursed Bullets instead of Ichor Bullets(if in a corrupted world), as well as the Optic Staff. Do NOT, for any reason, lead it to the surface, or anywhere outside the jungle.