Instructions
Open the map you would like to edit the spells for in "Warcraft III World Editor." The program is available from the game's directory in the start menu. To open the map, choose "Open" from the "File" menu on the top toolbar.
Press the "F6" button to bring up the Object Editor. A list of items and units in the game will be displayed.
Click the "Abilities" tab at the top of the window. The list of spells included in the map will be displayed.
Right-click the "Standard Abilities" folder. A list of options will appear.
Click the "New Custom Ability" option. A window will appear displaying the names of every spell found in the game.
Give your new spell a name and click the name of the spell you want your new spell to look like when it is being performed. Once finished, click "OK" and the spell will be created and highlighted. Its detailed information will be displayed on the right side of the screen.
Edit the details of the spell on the right panel to fit your preferences for the spell. You will be able to edit the damage of the spell, the mana it costs, and even the level heroes must be at to acquire the the spell. To edit the information, double-click the preference you would like to change. A list of available options will appear. Click "OK" to close the window.
Close the "Object Editor" window and save the map to keep your changes. To save the map, click the "Save" option from the "File" menu on the top toolbar.