1) Take an unit and duplicate it
2) Set the duplicated unit's range to something around 4
3) Set its weapon to 'Photo Canon'
4) Enjoy!

Example map attached.

Some precisions about the map:
- You can heal where there are Force Fields (but you must leave and re-enter to heal again)
- I've added a basic life regeneration ratio for your units
- Every point of damage dealt regenerates 3 shield points (which is a 100% regeneration since the shield is set to 10 and their attack is > 3)
- The unit I've decided to use is the zealot: it gives it a feel of "throwing balls", it's very neat
- I've also increased their movement speed and attack rate
- Use micro

Hey payne can the attack thingie be changed via triggers?

Quote from Tempz;)

Hey payne can the attack thingie be changed via triggers?

yes... you can change nearly everything via triggers (or at least pretty much)

I played around with payne's map a little.
Changes: Unit that heal are scaled 200%, increased speed of unit by 2000%, a new weapon(just more damage and longer range), and a changed cursor when you have the cursor over the units

In addition, when you left click and explosion appears at your mouse.

The best unit I've made so far is a super fast reaper that uses a void ray's weapon

Quote from Leeroy_Jenkins;)

The best unit I've made so far is a super fast reaper that uses a void ray's weapon

This means you prefer mine? =D