Chapter 307

A Devil's Heart (悪魔の心臓) is the 307th Page of Yūki Tabata's Black Clover.

Summary
Zenon Zogratis requests a devil's heart. Beelzebub chuckles and asks what it will get in exchange, to which Zenon offers his entire body, as well as his soul if their original contract still stands for the continued survival of the Spade Kingdom. The devil agrees, and the new heart transforms Zenon's body and heals the hole in his chest. The transformation stuns Yuno and Langris Vaude, and they note how similar he is to a devil now. Zenon boasts about the increase in his strength and demonstrates it by trapping Yuno in a spatial cube and assaulting the vice-captain with bones. Yuno tries to defend with Spirit of Boreas but is overwhelmed, receiving multiple injuries. Zenon criticizes Yuno for not being willing to sacrifice Langris in order to kill Zenon with the arrow. He then attacks with several bone whips that knock Yuno through a wall and knock him unconscious.

Langris stands back up and raises his Mana Zone, so Zenon attacks him with whips as well. However, the whips miss when Finral Roulacase appears in Langris's Mana Zone and warps his brother and himself to safety behind Zenon, who recalls Finral. Langris bristles at Finral saving him again, which Finral refutes, claiming that he is there to stop the man who abducted his captain, although in truth he did jump in without thinking when he saw Langris in danger. Mentally, Finral apologizes to Yami for taking a detour. Zenon traps the brothers in a spatial cube and attempts to skewer them with bones, but while in Langris's Mana Zone and holding onto Langris, Finral can instantly warp them out of the cube. Finral proposes that together they can fight Zenon, which Langris finds insolent but takes hold of Finral's hand.