I've been testing "song of silence" out on a Sword Muse in the beta. It seems to be broken because it does't land at all; even with someone void of buffs, jewels and armor. I've tried this about 10 times and wasn't able to get it to land even once. Also I timed the re-use time on the skill and it was upwards of 3 minutes. The L2 wiki says its a 2 minute cooldown / recast time. I'm pretty sure the cooldown is longer than it's supposed to be and also it does not work/land.