Personally I find the Fear/Charm spells to be the most broken ones; and having tried a few other servers, it seemed the same issue was going on elsewhere, too...
Good example of charm would be a fae drake emperor (
http://eqbeastiary.allakhazam.com/search.shtml?id=3684). I was camping the wood elf chick for the Paineel cleric quest, parading around lesser faydark, killing whatever I saw roam. Engaged a plenty of these buggers, and at lvl50, I was being charmed by lvl16 enc mobs. Pretty much a 50/50 probability of them landing it. It usually broke pretty fast, but the fact that it lands is absurd. Wasn't wearing any bigger resist gear, so I'd say my MR was around 70. At lvl20 or so when you'd imagine yourself fighting these, that should be plenty enough to handle it. Add to that the resists of me being more than 30 levels above them, and the charm should land like 0.1% probability. Hell, do lvl16 encs even have a spell to charm anything above lvl40? =p
And then there's the lovelies of Fear/Hate.
Here's a good example: I was going around there with 180MR: aggroed 2 ire ghasts + some others at one point, FD failed and stood there to die... I resisted both of their HTs, few rounds of shroud of hates, some other crap like their dots or something, don't remember. Alot of times I found myself resisting HTs and whatever, some caster nukes (cleric nukes, revenant nukes, revenant choke-line spells, bard songs from banshees...). But whenever the ghasts would cast Inspire Fear, it's like I can resist it with a meagerly 1/6 possibility. And it'd stick for a full duration just about every time. Same with toads in Fear, the buggers just fear kite you around the zone for ages and you resist it once a decade, only for them to recast it the next second and land it again. More of the same would be going on with the shadowknight-mob Crusaders in Cazic Thule: they conned high green green to me while I was hunting them, and they kept landing fear just about every single time they'd feel like casting it. Everything else they or their chums threw at me was being resisted easy peasy.