((I did mean Sacred Healing - it's from the PHB2.  It costs a turn attempt, and gives a +2 bonus per die on the damage healed by any conjuration(healing) spell [And, less relevantly, gives a +5 bonus on heal checks].  Since it's per die, and CLW Mass is only one die, it's only a +2 bonus for that particular spell.  Augment healing does sound noticably more useful, but I've never heard of it before, or I probably would've taken it instead))