izuni I never payed attention (since i completely ignored this skill so far haha) but its as short or even shorter than 16th night iirc. Basically you need to constantly recast it and that's extremely annoying and barring impossible when you are farming with kunai rotation in high density mob fields, cuz even the slightest tap from a mob will most likely gut your attack when you cast DC if you are not paying attention and it can even screw you when you are mid casting.
So currently the safest choice is to completely ignore it.
BUT, if this gets implemented..make it only a pvm mechanic, this skill also serves as an extremely annoyig pvp disturbance skill, so you prolly gutting its pvp/bg potential if you change it one sidedly.