This tutorial requires Warcraft III The Frozen Throne.

We are going to make a split shot ability based on barriage. Theres a few things you need to do to 'prep' the ability first.

Create a new ability for Multiple Shot

-In the object editor, make a new custom ability based on the unit ability Barrage.

If you would like a hero skill with levels:

-Change the field that says: "Is hero ability" to true.

-Save and restart the editor so it can categorize it properly, and so it shows 'art-icon-research'.

Now lets change Barriage so it works with our unit.

-Make area of effect the same as your units range, so the multiple shot doesn't shoot farther.

-Change the missile speed and missle arc to the same values as your unit.

-Set the desired ammount of damage.

-Remove any techtree requirements used for the ability.

Last, we calculate the number of targets we want.

-Unit already gets 1 for normal attacks.

-Unit already gets 1 for having barriage.

-Unit already gets 1 for the number of targets.

-If you change number of targets to 0, the unit gets a LOT of attacks.

So the minimum number of targets you can have is 3, and the maximum is somewhere around 9. Here is an image of an archer tower with multiple shot.

Give this ability to your unit and it will use it automatically when acquired.