Currently Mystic Raid Set is the worst option for raid sets...
Aside of having low mag, mystic raid set does not have a complimentary set to fill the weapon slot(s). Partial manashard set can only fill so little stats,
Miracle also does not help Mystics survives because skills won't one shot them, and trigger attacks will still kill them.
Increasing def and HP through talent also beats the miracle's purpose because Miracle can only be activated above 75% hp. Increasing Def and HP will increase mystic's survivability but will drop down Miracle activation rate possibly to 0%.
So I suggest to change Mystic Raid Set's skill bonus from Miracle to Dodge. Aside of increasing Mystic's survivability drastically, this will also encourage people building more diverse Mystic formations.