Please I need away to make his Np, or more of his cards Buster, so he can do a buster chain..

Also whatever happened to that person who level 120'd both versions of him?

Saber because his play style is more unique. Buff his NP to have 3 turns on the Atk buff instead of 2, get rid of the demerit, and add an extra Buster buff as an Overcharge effect, or maybe some kind of survival and he'd be serviceable. Caster has too much competition for any kind of buff they would be likely to give him to make him stand out in any way.