Calocera is a materials in Divinity: Original Sin 2
"A mushroom that's notoriously forbidden in most wizard universities."
Calocera is used to create potions which boost intelligence. You can eat it to gain one intelligence for two turns. You can also use a poison source on Calocera to add 9 poison damage to it. Due to its rarity, you'll need to purchase it from merchants throughout the game if you want to stockpile large quantities of intelligence potions.