You can use a damage detection system and check if the effect should be applied when the unit takes damage.
If so, you give him item based abilities that give armor and health regeneration.
EDIT:
And indeed as IcemanBo wants to mention, this place is when you have a trigger or script but it doesnt work.
(In which case, you have to show it.)
If not, then the World Editor Help Zone is the place to ask questions of how to do it.