The stygian set has some serious issues. Given it's 200k gold asking price for the weapons, players might want to know about this!
The max magicka bonus is sluggishly applied. Sometimes it entirely misses cloak. See here:
https://www.youtube.com/watch?v=10Cm4Xu0QJ4&edit=vd
Notice that my max magicka is 35k, and remains 35k until the second cloak.
Think it's just an addon? Here's an alternative view using stock UI elements:
https://www.youtube.com/watch?v=sAScUMfelYw&edit=vd
In this video it entirely misses the cloak.
But it gets worse. Even when the max magicka is applied, tooltips update, but skills do not. See below:
https://www.youtube.com/watch?v=p20c8i3NNfA&edit=vd
In this video I demonstrate the tooltip value of dampen magicka, it's actual value (25% higher for 5 light armor pieces). I then go into stealth. Stygian waits a few seconds after I'm hidden, and applies max magicka. I demonstrate my tooltip dampen magicka value which is now higher. However, after casting it, it's actual value remains unchanged.