Making spells have missiles.

So if I want to give a missile effect to an ability that doesn't normally have one, like channel, do I basically need to use the projectile functions in the Caster System? And if so, how do I know when the missile has reached its destination, particularly if the destination isn't a unit/widget? Anyway I am assuming I need to create this missile effect one way or another, triggered from the ability being cast and then detect when the missile reaches its target and then trigger the actual effect of the ability.

Some missile functions in the Caster System have an option to wait until the missile reaches its destination (be it a unit or the ground).

As far as I can tell, only Collision Missiles have that feature and they don't support parabolic trajectories. But true, it does work without a unit target.

So is this my only option if I want to create a custom triggered ability with a missile? That seems ridiculous. There should be a built-in event for when an ability hits a unit.

There are a lot of things that 'should' be. But when the ability is point targeted you can always use a formula to know how much time to wait, you know speed (projectile and unit) is the terrain units advanced per second of the object, the rest is easy once you know the distance between caster and target, right?

I'm not sure exactly what that part means, but true, I could use a formula for location targeted spells, but with unit targeted spells you could never predict the exact movement of the unit target so such spells would fire inaccurately. But I guess I am only really prevented from doing arching missiles that target units? That is not so bad I guess.