Naruto Master of Shadows

Styx the goblin dies and is reincarnated in Naruto, whether he is still a goblin, becomes a human or his bloodline ability is to transform into a goblin is up to you.

One route you can take if you decide to have him stay a goblin is that of summons. Being reincarnated to Naruto the closest thing to Amber is natural energy so all his new abilities would use that. Uniquely he can use natural energy to craft things. You can have Styx know how to make more goblins from his blood, and that if he makes contracts as a summon clan the new goblins will gain intelligence.

Look at the Styx wiki if you want to get a feel for his character and abilities, have fun.