The Talisman of Withhold is a bauble added by Thaumic Tinkerer. It is worn in the amulet slot and is activated on shift right-click. When worn and activated, it will absorb and store any experience points gained. When right-clicking with a Glass Bottle while not targeting anything will cause the Talisman to consume 10 experience points and turn the Bottle into a Bottle o' Enchanting.
After knowing that Zombie Brains have the ability to store experience, you have created a talisman that mimics that behaviour, not to a perfect extent though.
To switch the ability to store experience, you need to shift-right-click on the talisman. When the talisman is enabled, it'll absorb any nearby experience orbs, those can be transformed back into usable experience by right clicking with a glass bottle in your inventory, turning that bottle into a Bottle o' Enchanting. It must be worn in your amulet slot to take effect.