When does Allen walker from d gray man reunite with his friends after being killed by tyki mikk?

In "D.Gray-man," Allen Walker reunites with his friends after his battle with Tyki Mikk during the "The Book of Maran" arc. He is initially thought to be dead but later reappears in the story during the "Epilogue" after the intense conflicts, particularly in the "Fourth Exorcists" arc. His return marks a significant moment for the characters and the storyline, as they come together to face new challenges.