Destroy the right specialeffect

[Telemenekken]

Hey guys,

i have a problem with a small trigger. I want to make a spell which is stuckable and deal damage over 3 seconds. Now i have make a spell which is passive. Trigger is maked for the damaging. BUT i tried to make a specialeffect on the unit which will destroyed after 3 seconds. I tried to set variable and after 3 seconds destroy the special effect. But when the Hero ( which has this ability ) change the destination the variable will reseted and the other has an special effect until he die! How can i make it with "triggers".
Sorry for my english! Thank all who´ll answear me...

 

[Telemenekken]

Pls help me!! Need it fast pls

 

[T4COBELL]

Make a special effect variable and set it to Last Created Special Effect. After any wait command, last created... returns null.