I have looked at all the guides and I can't understand why I would ever do the true Thrust, Vorpal Thrust combo. I can spam Impulse Drive and do more damage overall. The combo hits for a total of 350 potency, in the same amount of time I can cast 2 Impulse Drives and do a total of 360 potency.

If I am missing something please enlighten me.

Any help is appreciated, thanks.