the firsts necklace seemed to surpress the fox' chakra itself, so it could be that the necklace and yamato are able to restrict the fox on their own and work just better together.
i could imagine that pains newest technique is a sealing technique or a special technique against jinchuurikus. he seemed to be pretty sure of his victory when he pierced hinata.
i could imagine that pains newest technique is a sealing technique or a special technique against jinchuurikus. he seemed to be pretty sure of his victory when he pierced hinata.