Brain of Confusion

Every hit an enemy lands gets a roll to be erased outright, damage and knockback and any debuff it would have applied. A brain flies off your character when it fires, so you can tell it apart from a lucky miss. The catch is the short lockout afterward, which sits in your buff bar looking like a debuff while doing you a favor: it raises critical strike chance and summon damage for its duration. You cannot dodge again until it expires, so this saves you from the first hit of a barrage rather than the barrage.

Taking a hit also scrambles enemies around you. The chance, the duration and the radius all scale with how hard you were hit, so a graze does almost nothing while a hit that nearly kills you turns the whole screen around. Each enemy in range rolls separately, which is why you usually see a partial effect rather than all or nothing. Confused enemies walk away from you instead of toward you, and that is exactly the gap you need after the hit that would otherwise have chained into a second one.

Over a long fight the two prevent about the same amount of damage, and they feel nothing alike. The Worm Scarf shaves every hit, which is steadier and better when a lot of small damage is grinding you down. This one offers a chance at taking nothing at all, which matters more when one hit is large enough to end the attempt. On the higher difficulties a reduced version of a hit that takes most of your health is still a hit that takes most of your health. If you want both, house the Dryad in a graveyard once you reach Hardmode, buy the seeds for whichever evil your world did not generate, grow a patch of it, and go kill the other boss.

It only exists in Expert and Master, where the Brain of Cthulhu puts it in the bag every time, so a Classic world never sees one. The dodge answers enemy attacks only: lava, drowning and fall damage go straight through it. The lockout cannot be cleared by the Nurse, the accessory ignores dyes, and stacking copies does not stack the chance.