User blog comment:Mathmagician/Hard Mode Bosses Solo Walkthrough/@comment-4698557-20111230154921/@comment-4674838-20120101075151

As I said before, you can technically kill the Twins with just hellstone, cross necklace, 75+ def and a weapon that kills them quickly enough (without dodging at all). It sounds to me like you're trying to go for it without heart statues and it's not working because you don't have all the requirements I listed and you're not making up for it.

In particular, your partial Hallowed Armor is not as good of a choice as FULL adamantite (gives set bonus). Also, your weapon (Star Cannon) is a great choice--if you have enough stars to continuously spam the star cannon from the minute you summon the twins to the time they die, without using any other weapons at all. Your backup weapons (dao of pow and flamethrower) are not good of choices against the twins, although they're great against the destroyer. If you don't have enough stars for your star cannon, then I highly recommend getting crystal storm or the megashark. Crystal storm, megashark, star cannon are generally the 3 best weapons to use against the twins.

I'm guessing your defense is kinda low (50 ish?). You need to make up for this with better healing. You need heart statues or you need to build a house for your nurse near the skybridge and then teleport to her with magic mirror to heal.

The hellstone strategy is extremely good against the twins and it will beat them, you just need to fix a few problems with your equipment / strategy / execution to see it.