Kislevites are magic resistant by nature, comes from living so far north and ingesting so much chaos energy. They don't quite glow (but that was joked in one or two canon pieces), but they are most certainly not your standard old world humans anymore. It's a similar story with Lizardmen they are not exactly all magical resistant, they are just very disconcerting to cast against, probably because they are not natraul creatures and because of something the old ones did to them. (Half the Kislevites are nomadic the rest are city builders, and before you ask Kislev City has never fallen to Chaos, and it's built of wood, Middenheim with the full might of the Empire's armies etc built into a giant crater with multiple walls has nearly fallen twice).
It's also interesting to note with the Winds of Magic, how they don't penetrate in Brettonia or over the worlds egde mountains much, Troll Country is like how it is because there is no barrier to chaos, Kislev is still safe because it has mountains and distance in it's favour, Ulthanuan is only safe from Chaos magic because elves are tricksy and built protections into the place, same with Albion, otherwise they would both be swallowed up with chaos magic. The winds are a geographic thing, the Slann are so powerful they can use them from thousands of miles away, while the Damsels in Brettonia only gain powers (or there knoweldge) from a demi-goddess.
It would also be kind of cool if they had a chance of exploding when they attack with a spell, so you cast fireball the mages head explodes because he/she/it has drawn to much power and made an inferno... (think dead unit+damage)
It's also interesting to note with the Winds of Magic, how they don't penetrate in Brettonia or over the worlds egde mountains much, Troll Country is like how it is because there is no barrier to chaos, Kislev is still safe because it has mountains and distance in it's favour, Ulthanuan is only safe from Chaos magic because elves are tricksy and built protections into the place, same with Albion, otherwise they would both be swallowed up with chaos magic. The winds are a geographic thing, the Slann are so powerful they can use them from thousands of miles away, while the Damsels in Brettonia only gain powers (or there knoweldge) from a demi-goddess.
It would also be kind of cool if they had a chance of exploding when they attack with a spell, so you cast fireball the mages head explodes because he/she/it has drawn to much power and made an inferno... (think dead unit+damage)