Mana Potion

Mana Sickness lands the moment you swallow it, and the penalty deepens each time you drink again before the previous dose has faded. Panic chugging three in a row leaves your magic damage badly cut right when you needed the mana in the first place, which is the opposite of what you wanted.

Mana regeneration gear, a Mana Flower and a wider mana pool exist so you never have to reach for one mid fight. Treat the potion as a way to top off between waves or after a long tunnel, not as fuel you burn during a boss. If you are drinking these constantly during a fight, the fix is more mana capacity, not more potions.

Crates hand them out steadily once you start fishing, and the Merchant stocks them once the world goes hardmode, so there is rarely a reason to farm ingredients for the middle tier yourself.