Ignoring fractal, I think the card is fine. It's reasonably costed, has a useful but not OP effect, and I could see myself using them in a deck. With fractal, though, it might get kind of crazy, although they do get smaller with each use. For example, six of these would deal 21 damage, and it would take 14 to pass the magic 100 damage mark. I'd have to see it in action to be sure, though.
Two ways to fix the fractal problem (if it is a problem) would be either to not allow player targeting, or to change the activation element to something nonair (and nonaether) so that you'd need to do at least a trio to make it work.
Also, I'd imagine that reflective/emerald shield would reflect the damage if done to a player.