#1 - July 25, 2017, 11:11 p.m.
However, it completely removed any Mastery interaction from the set. The 2 set bonus could just as easily read "The primary target of your heals gain the Tranquil Mists buff...". There is no reason for Mistweavers to increase Mastery rating with this set, as there had been in the previous iteration.
The 4 set bonus is terrible. Yes, it's no longer at odds with the 2 piece, but the actual healing of it is not nearly enough (in the current build) to warrant taking less well-optimized pieces for its effect. 25% Spell power is nothing, especially on a 15% chance. It needs to be made more consistent and actually impactful.