Chapter 306

Boundary (境界) is the 306th Page of Yūki Tabata's Black Clover.

Summary
Yuno fires his Spirit of Euros spell and manages to pierce Zenon Zogratis's chest. As Zenon thinks about how powerful that spell was, Yuno proclaims that their tenacity won this fight.

Zenon thinks back to when he was injured and his siblings, Dante Zogratis and Vanica Zogratis, insulted him for being weak. Zenon's oldest brother tells Zenon to not worry since Zenon has the greatest aptitude for being a devil host like him. Sometime later, Zenon is being assaulted by John, whose father is in the Mage Defense Force, because of his Bone Magic. As John goes to attack Zenon again, Allen shows up and stops him. John and others run away, which Allen calls them an embarrassment to the Mage Defense Force. Allen introduces himself to Zenon and mentions how strong Zenon's magic looks. Allen and Zenon then head to a roof top, where Allen comments about the situation the Spade Kingdom is in. Allen proclaims that he will be the commander of the Mage Defense Force to give hope to the citizens of the Spade Kingdom, which Zenon says that he will also become the commander of the Mage Defense Force. Allen says that that makes them rivals and that they will compete to see who become commander first.

Over the years Allen and Zenon train to get stronger and receive their grimoires. Zenon even apologizes to his oldest brother since he does not want to become a devil host. Allen and Zenon manage to get into the Mage Defense Force and are assigned to the fourth division. When a dungeon is discovered within the Spade Kingdom, the fourth division head out to explore it but find a devil. Zenon figures that he can defeat the devil with his ultimate spell but notices that the devil has no openings. Allen says that he cannot lose here since he is going to be the commander of the Mage Defense Force. As Allen charges, Zenon says that Allen will die but notices that this is his chance to kill the devil. Zenon also figures that he will kill Allen too, and thinks about what would happen if he does not kill the devil. Zenon decides to use his spell and kills the devil, along with Allen. Zenon thinks about how emotions and tenacity mean nothing without power and starts to cry. Zenon starts to thinks about how power is everything and how the weak should be discarded. Zenon also starts to wonder about the power of the devil and asks his big brother to make him a devil host.

As Zenon drops to his knees, Zenon meets with his devil, Beelzebub, and says that they should make a deal.