To be blunt, it seems that vortex spells (excluding those that stay still like Pit of Shades, though even those have become rarer of late) are not great insofar as spells are concerned: while people do still bring bound vortex spells (See Slann and Volkmar Banishments), when it comes to the normal version of the spells they only rarely see competitive play.
Looking at why this is, it becomes apparent that, while their damage is nothing to scoff at, they have problems with control and predictability: after being cast, they move at complete random. This leads to a problem when compared to similar damage spells: why use flame storm when the pendulum or flaming skull can produce similar results without the risk of the spell either going nowhere useful or backfiring and damaging your own army? Sure, one could try to argue the damage and disruption is greater, but the complete lack of control turns vortexes into roulette games which, generally, don't go in your favor. And since, if the vortex misses badly, you waste precious WoM, it's better to not play that game at all and instead stick with something significantly more likely to hit. As such, most vortexes are not considered competitive and thus are not generally brought.
There is a rather simple solution to this problem: allow the player to control the initial direction of the vortex.
There are 2 ways to do this:
1) Have vortex spells be cast like wind spells. Basically, when casting you can control the direction the vortex initially goes the same way the direction of wind spells are controlled. After casting, the vortex will move in that direction initially then resume it's normal random movement.
2) Have vortex spells always initially move away from the caster. In this version, the spell's initial direction would be directly away from the caster, then the spell would resume it's normal random movement.
Either solution would make vortexes more viable, as the initial direction could be controlled and thus friendly fire/complete misses would be less common. It would also allow for actual counter-play, as the opponent could see what direction the vortex would initially be going and move troops accordingly (instead of currently where the opponent just moves their troops out of the initial zone and hopes the vortex moves in a different direction). I personally think 1st suggestion is preferable (avoids the problems that made Warhammer 1 wind spells difficult to use), but some might see that as too strong even if vortexes were nerfed a little in compensation, hence the 2nd suggestion.
Also, on a side note, CA can you please lower the WoM cost of Command the Unliving Overcast? The poor Strigoi Ghoul King has to pay 3-4 more WoM for strictly inferior Crypt horrors compared to the Manticore/Rotten Promethean summoning spells respectively (16 WoM for Command overcast vs 13 for Transformation and 12 for Denizens) and gets them for less time. A longer duration and/or lower WoM cost would be appreciated!