Cold snap and evocation heals according to your current health and not your max health. For example cold snap heals 140k at max health and at 50% it heals just 90k. So I guess it´s bugged more ways.
Could anyone please report it?
Edit: I found out that alter time is bugged too.
It never returns you to your locations before 6 seconds.
Cold Snap healed me for 127,089 when I was at like 20% of my HP. And when I was fully regain it healed me for same amount so I don't think anything is bugged here.