Using Damage detection system is the best way to do it because you can easily manipulate damage done to your liking.
You can, of course, try to make your own damage detection, but it will probably be a lot buggy, and less efficient overall.
Also, things like damage detection systems or unit indexing systems are created and posted here for other people to use. Using and understanding other systems (mainly those that have been approved by many people) will increase your own understanding of triggers.