I have an idea.But I like the idea! For me it would be enough to let the dots tick a bit harder in general. And perhaps a little buff to the power lash. In this case i would not miss a real finisher.
And it wouldnt be OP cause u can't spam power lash. You have to time dots and your power lash (and u need to cast another skill like talons, deep breathe or fossilize before, so no-one can say its a cheap, spammable skill)
There are some sets, that make dots more effective. But with most of them the power lash is a wet noodle.