A troublesome process

I'm currently working on a solo project for a Team Fortress 2-esque map and have hit a snag with an ability I would really like to see put into the map.

What I want to do:
Have an ability with a targeting system like "Blizzard" or "Flame Strike" that deals instant damage to one target. It is going to essentially be the Sniper's "Snipe" ability. When activating the ability the targeting reticle comes up (I don't need any new art for the reticle, what the game provides is good enough) and you can move it around the map normally, then when someone enters it you just left-click and it hits them for a set amount of damage and then starts its cooldown process.

If anyone could give me any tips or lead to me to where I might be able to find some, I would be much obliged. Thanks.

Tried Finger of Death yet? It's basicaly a single-target damage ability.

If he wants the reticle, Finger of Death won't work so hot.

Options:
Change Flamestrike to have no casting time.
Change Blizzard or Rain of Fire to have only 1 wave with no delay.
Make a Channel-based ability with a reticle and trigger the damage.

Thanks Panto, I will try it, though I remember making a similar attempt with Blizzard concerning the waves, and the damage came out, but there was no animation. How might I be able to change it from the shards of ice to a single arrow animation?

I tried editing the effect and buffs, but nothing happens when I cast the ability, save for the damage being dealt.

To make blizzard into a single shooting arrow is pretty simple;
Casting time, delay time etc to 0
1 wave
set the Art;Projectile to what ever u want, alone with the arc and projectile speed. Then just change the Animation feild (right at the top) to Attack, and bam!
Now you have an area targeting arrow attack!

Excellent Gorman, that did it! Thank you both very much. I hope to provide you with something fun to play when I am finished!