tml616, I have already tried that solution and it works. But my map is too big, with many stun buffs and triggers, when I made that is causes too many lag because it have to check periodically the buffs.
But Xiliger gave me the solution, check it when a unit starts an ability, so it wont cause lag!
If someone is interested in this topic and want to know here is the trigger
Event: A unit begins casting an ability
Condition: UNIT Equal to Target of ability being cast
Action: Unit remove STUN BUFF from UNIT
Wait 1 second
Unit remove STUN BUFF from UNIT
Wait 1 second
Unit remove STUN BUFF from UNIT
Wait 1 second.
Unit remove STUN BUFF from UNIT
The waits are because the missile delay a little depending how far are you or how closer are you. Example: Storm bolt
However, I still need help because there are some spells like Cluster Rockets or Volcano that dont have target but stuns. Can anyone help me?