they've already said what u need.. but
let me elaborate more precise XD hehe

so, in order for u to get the "Bloodsuck"

u need to get "soul dodge" skill first. hmm.. u get that from welling leader after u finish the quest he will give u. i think thats the tiger quest? yeah.

and... after that, when u have the "soul dodge" skill.. u go to china and talk to the old man outside the city, he is near the bridge. he will ask u to kill the freakin tigers again i think?? (yeah. im starting to think that this skill must be named tiger skill instead of bloodsuck.) and after that. come back to the old man and he will teach u his super duper flying technique. i mean... bloodsuck XD.. if u want pm me ingame. i'll help ya.

and thats about it ^^