Gon transforms into a leopard by using a seal that a stranger gave him.

This transformation not only increases Gon’s physical abilities but also provides the energy required to use his technique, even though there is little time left. In this form he is able to easily defeat Neferpitou and its puppets, who were impossible for him to beat as himself or at least requires much more effort and an unusually long time to defeat them before being transformed.

However it’s unclear if he will be able to attain this power again in the future given that the person who gifted him this seal was shot slain by Pitou earlier on in the fight after just a brief moment hesitating before finally shooting it down.