if you just want an ability to go out in all four directions w/ a trigger theres a few steps to do. Warning ya though, i havent messed with WE in quite a while, and im just now getting back into it, so this might not be the BEST way, but this is how i would go about doing it.
FIRST: Make an dummy ability, just some random ability, can be anything, but make sure it has the icons and descriptions you want it to have, then give it to your hero. note: this is NOT the ability that will actually do the damage or create the models, it will be used so that we can later detect with an event when the hero is casting it, and do the rest with triggers. Oh, and make sure this ability doesnt do damage and doesnt have any visual graphics other than the icon.
SECOND: Make a dummy unit (a unit that has no model file, shadow graphic, no attacks, and has can flee turned to false. Also make sure that it has the ability Locust, so it is untargetable)
THIRD: Make an ability based of off crushing wave, and give it the stats that you want, descriptions and icon dont matter here.
FOURTH: Make an event that detects when the hero casts your ability, (the one you made in step 1). Then, for the actions, make it create 4 dummy units, one for each direction relative to your hero (left, right, up, down) and give each of them the ability you made in step 3. Finally, have each dummy cast it in different directions, and theres your 4 directional crushing wave!
Remember, like i said before, this probably isnt the best solution, someone with more experience than me will prolly come along and tell you something much more convienent and simple. Still, the way i see it, your thread had no replies, so this will at least be a conversation-starter, and help you get your question answered!