Jungle Hat

Jungle armor is the pre-Hardmode magic set, three pieces, and its whole reason to exist is mana economy. A wider pool, cheaper casts, and a solid bump to magic critical strike chance. At this point in a run that is the difference between a caster who can keep firing through a fight and one who spends half of it standing still drinking. The full set also leaves little grass particles trailing behind you as you move, which is the only way anyone can tell at a glance.

Everything comes from one trip underground. Jungle Spores are the glowing bulbs stuck to the walls down there, Stingers drop from Hornets and Spiked Jungle Slimes, and Vines come off the Man Eaters hanging from the ceiling. Take a hook and a weapon with some reach. The Underground Jungle at this stage is considerably more dangerous than the caves where you would otherwise be mining ore for armor, and that danger is the real cost of the set.

Compared with Gold armor, which sits at roughly the same point, Jungle gives you more of what you can actually use as a caster even though it costs a trip. Platinum is the honest competitor: more defense, nothing for magic. If you are swinging a sword or shooting a bow, take the metal and skip the jungle.

Ancient Cobalt armor is the same set in older clothing. The pieces mix freely with Jungle armor and still complete the set bonus, you just lose the grass particles. You can also transmute Jungle pieces into their Ancient Cobalt counterparts through Shimmer if you prefer that look.

It will carry a mage from the first jungle trip through the pre-Hardmode bosses without complaint. Meteor armor takes over if you commit to the Space Gun, since that pairing costs nothing at all to fire, and once Hardmode opens the ore headpieces replace it outright. One last oddity: the hat is the cheapest piece to make and the one a vendor will pay the most for.