Mana Leech

The Mana Leech is a Pre-Hardmode mage accessory. Every weapon that has a mana cost now costs 30% more mana, but in return it grants +20% magic damage. Some of the increase can be nullified by using reforges that lower the mana cost, so keep that in mind.

It's obtainable by fishing in the Glowing Mushroom Biome.