It depends on your playstyle. In dungeons or the open world, it makes sense. I usually have it in my template for my classic thief too. Especially since tracking isnt worth much anymore.
Magic Resist is pvp oriented. If you're a good thief, they won't get a spell off before you've high tailed it away from them. Carry magic trap pouches for paralyze. I can't say it's a usefull 100 skill points for a PVM oriented thief. pvp thief, it's a must have. ---- Your whole life as a thief will revolve around the 10 second cooldown timer. Hide -> count to 10 -> Stealth -> count to 10 -> restealth as needed. Snoop -> Set last Target on Item -> Use Stealing -> Count to 10 -> Target Last Target -> Run -> Hide wait 120s, bank goodies, repeat. Also if they see you hide, they could cast reveal. So hiding while running is a skill, Run -> stop very quickly, say behind a tree -> Hide & hope they didn't remember the exact tile. People without magery will try to bump into you to find you. My wording may not be perfect but you get the idea. Start learning to count 10 seconds in your head on every skill action.
At least I provided the option you did as the only viable one! Have I told you what a noob you are and how ashamed I am of you!? I bet you don't even know how to steal blessed sandals that are worn either??
In my experience with GM Resist on thieves it is a waste of the slot.. best to use the skill slot for something you will use more or for simple magery to make pop boxes for the pesky para-attacks. Now on a run-and-gun thief like a fencing poisoner... keep the resist to allow more HP when you run away to hide if they counter the melee attack w/o panicking.
