Pain Suppression seems much too powerful for what we're used to in HOTS, it's like Lt. Morals safeguard but with twice as much damage reduction & cast able whilst stunned, I would consider revising the stats of that ability. Love the idea of the passive, good thought on the shadowform & "light"form, only problem is though there isn't a stat in HOTS called "armor" like in WOW, so perhaps just having "you take 10/20% less damage" whilst in shadowform...

The first talent Frigid Alteration seems a little too strong, by the 20th minute you'd have 40 hp / second with just the stacking passive, with the regeneration globes on top of that you could have upwards of 80 hp/s by the 20th minute. I feel like this could be slightly busted.