150 potency, 0 mp cost. It's a great DPS tool when used considerately, if something is immune to knock backs or I know that something is going to die as or directly after I use it, then I do so.
As far as prioritising CC goes, I suspect that stems from newer healers simply not trusting tanks to get agro on everything. A low levels this is a pretty fair stance to take. Easily solved with a bit of communication imo!