Making a projectile ability that targets a point, not a unit?

I have this idea in my head for an ability that fires a tracer onto a point, and then a different unit entirely fires the actual damaging projectile. For the effect, I need to have an actual projectile fired, and then I need the attack trigger to execute immediately when the shot lands. So, I'm trying to think of a way to do this =)

I need a good dummy ability (something that fires a projectile onto a point, but cannot be targeted onto a unit.)

The actual attack is going to come from a unit that follows the caster around all the time, I guess a simple thing to call it would be a familiar, but it's only for aiding in spellcasting. (It's a pretty cool effect, the "familiar" does all the work while the caster essentially just issues it commands 8)))

One last thing. Is it possible to give a unit an attack 1 and attack 2, but force it to use one or the other under certain circumstances? I'm curious about that as it may be helpful to me for this.

I would use a Ward ability... something like a Serpent ward would designate a point. The ward would be invisible - you could make your own "projectile" travel from the caster to the ward's spot, then have your "familiar" cast the spell on the ward, or the ward's location.

Hm, ward ability... do those actually make a projectile? If not, the only way I could think of to create a projectile would be to make an invisible unit fire it from the position of the caster onto the point. (Which would be easy, but I've noticed that doing that doesn't always have the smoothest effect.) I was hoping for a way to do this without doing it that way, is there another way?

No ward abilities don't have projectiles.

What I would do is, when the caster casts the ability, have an invisible unit created at the position of the caster, attach whatever special effect you want to it, and order it to move to the ward. Then when it gets close enough to the ward, either kill it or change the effect or whatever, then order the familiar to do the attack.

Hope this is of some help! Good hunting.