Chaos Doll

Chaos Doll (聖魔人形) is the evolution that Beretta gains as a gift from Rimuru's Harvest Festival. At that time, Rimuru was still his primary master while he simply under Ramiris for a limited time contract.

The evolution happened because of Rimuru's fear of being unable to do anything within the Holy Field was transmitted to Beretta, causing him to gain a Unique Skill and Chaos Core associated with being able to resist the holy element as a Magicule-based existence.