Arcanum of the Caster

The Arcanum of the Caster is a post-Moon Lord accessory that acts similar to the Mana Flower. However, instead of applying the Mana Sickness Debuff, it instead applies Caster's Sacrifice, which increases mana usage by 20%. This can stack up to 5 times.

It can only be obtained from Erazor's Treasure Bag on Expert Mode.