Star Veil

Doubling the window where you cannot be touched is worth more than it sounds. Contact damage from something sitting on top of you goes from a rapid drain to one hit you can walk away from. If you also run a dodge accessory like the Black Belt or the Brain of Confusion, the extension applies to the dodge window too, which gives you a long stretch of free movement to reposition after a mistake.

Taking a hit drops a small volley of stars around you. They hurt, and they cut through armor, but they only appear when something has already connected, so building around them means building around getting hit. Only one star effect can be active at a time, so wearing the components alongside it adds nothing at all.

Melee builds that stand inside the fight get the most from it, because they are the ones cashing in that invincibility over and over. A ranged or summoner player who rarely gets touched will do better with a damage accessory. Both halves are Mimic drops, so a hardmode Mimic farm is the only route to it.