User blog comment:CaptainLocoMoco/Please help me figure out how to kill the destroyer!/@comment-221.127.249.109-20111209154049

You can:

Set up an arena, use the Dao of Pow, Excalibur, Rainbow Rod, or other high damaging weapons. Spam mana potions if you are a pro magic user. Demon Scythe or other piercing weapons is great. Megashark w/ Crystal or Cursed bullets work excellently.

You can also: bury yourself in sand, so you keep on taking damage (using cross necklace is good), with Cobalt, Mythril, Adamantite or Hallowed armor set you will only take 1 each time. You'd only need 2 or 3 Greater Healing Potion. That way you will be invulnerable to damage from the Probes or the Destroyer itself. I recommend this way, as its economically efficient, and is easy.