Ash Wood Helmet

Ash Wood comes off the trees scattered through the Underworld, so the outfit is available the moment you can survive down there long enough to swing an axe. That timing tells you what it is. Defense on the full set is thin next to anything else you could wear by the time you reach hell, and the bonus does nothing against enemies. It is a mining kit.

What it does do is take the sting out of a lava dunk. Falling in hurts about half as much, and the burn clears in a fraction of the usual time. A mistimed jump over a lava lake becomes an annoyance instead of a run ender while you dig hellstone out of the walls.

Wear all three pieces alongside an Obsidian Rose, or anything built from one, and lava stops hurting you entirely, damage and burn both. That pairing is the honest reason to craft the armor, and it is far easier to arrange than hunting a Lava Charm.

One catch. The immunity does not protect your timed protection. Something like Lava Waders still burns through its grace period while you stand in lava wearing this, so you can wade out feeling safe and find the timer already spent.

Remix and Zenith worlds rebalance it. Each piece gives almost nothing to defense there, so any pretense of this being armor is gone, but the lava reduction is stronger than anywhere else. The burn cut looks worse on paper only because lava burns you for much longer in those worlds, so the same saving buys a smaller share of a bigger problem.