I would say that if you play magic stalker or any magic class you have to be prepared to face Golden Thief Bug,it's inevitable. Magic stalker is a build/class where you think outside of the box but are punished for it,Professors share the same fate,Ninjas are perfectly fine on there own(depending on how you play them),Soul Linkers are a little different so i won't go into them but Professors have Stave Crasher while Magic Stalkers don't but Magic Stalkers do have the versatility with backslide,however if you compare Magic based Stalkers to Dex based Stalkers their a joke. Buffing the magic based stalkers won't hurt anyone at all, i can't even remember the last time i saw a Magic Based Stalker.
Adding one of these skills: + Add another magic skill to the sword. o=One OR MORE of the following skills, being reasonable about them of course, would certainly help. --> Soul Breaker - Lightning Spear Of Ice - Acid Demonstation - Storm Gust - Meteor Storm - Jupital Thunder - Stone Curse - Mind Breaker (Yeah, mind breaker. ) - Crimson Fire Formation - Dragon Fire Formation - Falling Ice Pillar - Lightning Crash - Magic Crasher.
And maybe buffing the sword stats or magic damage could help. Almost no matter what you do will make this class/build completely overpowered.