The Serpentarius spirit was the master of Skybinder.
[LV1-LV2-LV3] When Summoned
Discard the top three cards of your deck. Then, select a Skybinder card from your trash and add it to your hand.
[LV2][LV3] During Your Attack Step
When this spirit or one of your Skybinder spirits attacks, select one of your opponent's spirits. Remove a core from it and place it into their reserve.