"[Auto] [Valid] Square [Trigger] At the start of the Main Phase of your opponent's turn. [Effect] If you have 4 or more [Mermaid] in your Resource, you may choose one of your [Mermaid] in Square, and return it to hand. If you do, you may choose a Cost 5 or less [Mermaid] in your hand, and make it appear in empty ? Square as Reboot."