Triggering help needed

Im using mana shield as start the effect of an ability event and the actions : i add 3 abilities to that unit.

I want when deactivating the mana shield to remove the added abilities. The only thing i can think of is - a unit has Buff equal to false. As you know when the mana shield is deactivated there is no buff. Yes but when i use another trig with 'even: none' C: (CasterVariable(this var comes from the trigger where casting unit starts the mana shield) has buff Blabla (activated) ) Equal to False

Remove .... ability from CasterVariable

nothing happens the abilities stay. What should i do to make it work?

Events: none means this trigger is never executed, irrelevant of conditions. One way to do what you want is to add event "every one second"