That's why you must ensure that the dummy caster does not have any abilities except locust. Then, you can just add the spell, and order it to cast. This way, it won't have order string clashes.
But, I didn't use the original shockwave for this. So, it should be fine. You can pretty much change the base spell to any point-target spell.
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.