Im not making a easy to use guide.
Edit - Made it one giant URL to reduce leachers.
Dont click this
Works on most servers.
Step 1 - Download cheatengine from cheatengine.org
Step 2 - Find the spell you want for no GCD, IE, soul fire rank 13, would be the Id 12345 ( Not really Don't want to wowhead )
-----------( MISSED STEP )------------
-Step ? - Take the spell ID and put it into scan, and then click first scan.
Step 3 - Copy all the address except the green ones to the bottem bar
Step 4 - Change them all to 50000
Step 5 - Freeze them all.
Shoot a sf no GCD have fun.