make it in a way the you pick units in a line and then change flying height up, then down.
try doing something like this:
advice, the way below is not MUI:
when the spell is cast you set 2 points (position of triggering unit + target point of ability being cast)
you turn on a periodic trigger that pick units in X range of (triggering unit_pos + any real (in algle of unit_pos to cast_pos).
picked units are addad to a group and are lifted.
when the trigger ends all units in the group takes damage.
this is easyer if you make not MUI, for sure, but you may use what you want.
I'm on a page about incorrect corrections, and spent the better part of like two hours trying to get someone to understand that -5^2 = -25, not 25, and then that post had comments get reposted because that group is self sustaining, and that person was in turn trying to explain what I just explained to them. And I'm taking that as a victory
I will be AFK for a couple of days you guys hold down the fort while I am gone. I will be checking in on my phone but that will severly limit me. Be back saturday!