We have the currently existing parameters:
Can fire indirect
No current CHARACTERISTIC restrictions.
The only thing going for it, is if you fire at a group of 11 models stuck between a cluster of large important units, and hoping the splash hurts them.
Vortex Missile Stratagem, at 3CP can boost the damage, but is very expensive.
So, we have quite a bit of flexibility to add characteristics for targetting.]
If primary target is a VEHICLE or MONSTER, 1 die counts as a maximum roll (6)
If primary target is TITANIC or has at least 20 wounds, 2 dice count as having rolled their maximum amount (12)
Granted the biggest limiter is the completely average base hit roll of 4+...