Ren is haunted by the deaths of his party members in a failed attempt to defeat the Spirit Tortoise, and doesn't want to believe that he might be responsible for what happened.  Myne seems ready to take his side and support him, but...
My strongest is much greater than this!
!يمكنني أن أصبح أقوى من هذا بكثير
Das ist nicht meine wahre Stärke!
¡Aún no han visto
por qué soy el mejor!
¡Aún no habéis visto
por qué soy el mejor!
Je vaux bien mieux que ça !
Non ho ancora raggiunto il mio picco!
Meu máximo é melhor que isso!
Вам и не снилась моя настоящая мощь!