Mana Regeneration Band

The number you actually feel is not the extra regeneration, it is the shorter pause before regeneration restarts after you spend mana. Without it, a magic weapon fired continuously keeps you pinned at empty. With it you dip, stop for a breath, and are back in business. That difference matters most on weapons you tap rather than hold.

What it adds is a flat rate, and your natural regeneration climbs with your maximum mana. Early on the accessory is doing most of the work. By the time your bar is near the cap it is a rounding error, and the slot is better spent on damage or movement. This is a pre-hardmode and early hardmode item that quietly retires itself.

Crafting it consumes a Band of Regeneration but keeps none of its healing. If you were relying on that passive trickle between fights, you lose it the moment you combine them, so make the swap deliberately rather than because the recipe was available.

The starpower half is Corruption loot, so a Crimson world cannot get it the normal way. Building a Graveyard unlocks a recipe that turns a Panic Necklace plus one Mana Crystal into the missing band, and in hardmode you can fish an artificial Corruption for crates instead. Both are more effort than the accessory returns unless you are still early enough to care.