I decided to check what level artifacts cast their spells at (it's 20, in case you're wondering), and it just so happens that I ended up in a situation where I hit myself with an area at range spell (from a Mark of Fireball) while under the effect of Spell Reflection. So, the question is, does your own spell reflection work on your own spells?

The answer is...

The game freezes if you try, at least if you have 100% spell reflection.