You haven’t looked very hard. It’s in the blue post when blizz announced the frost aura will only tick every 2 seconds.
As this guy said, why would you use amplify magic? If anything you’d want dampen magic to reduce the damage you take from the aura, not amplify magic to increase the damage you take. But really neither is great because you don’t want your heals to be gimped in a fight where you’re bound to take a lot of damage.