In order not to use Bribe's damage detection system or patch 1.35's inbuilt taken damage event and triggers, you could simply make a Resistant Skin type spell (or what's it called) that blocks 100% of damage and add it and remove it on the desired unit based on a periodic timer or how you see fit.
Also please note that if you are not asking stuff about triggers or the editor but just want others to do some things for you, you should use the Requests forum instead.