I put one merit into Assassin's charge only because I misread the info on it...I thought it said "causes your next attack to do triple damage". Anywho..about the only time I ever use it is when I'm farming attercop's as thf/dnc and want some extra tp/drain hits after a sickle slash connects. Or if I'm bored and just ***'in around.
It's not about how often you play it. It's about how well you play it. And apparently you don't play it too well if you spend half your time meleeing from the front. Not even SAMs do that, apart from WSs.