Basically, Rite of Rage covers redirected combat damage. This means that Martyr Golem and Guard can be used to abuse this.
I have to credit my friend Podian for discovering this. We tested this with a Martyr Golem having Rite of Rage, an Unstoppable character and a lot of defenders on the other side, including Magic Siphoners with 50 Power. Of course, the Unstoppable character's Power was higher than all the defenders' Health to make this work.
What happened was that the Martyr Golem gained Power and Health over and over again, resulting in 200+ Power and instantly killing me. Of course, this probably would not happen in a real game, but the abuse can be re–enacted on a smaller, but still significant scale.
This will also work on a defender and Martyr Golem or another character with Guard, since defenders have an Unstoppable–like mechanic by default. Build up as much damage as possible, redirect it and convert it into Power and Health, profit.
The problem does not lie in Martyr Golem, Guard, Unstoppable or the defender mechanic. Rite of Rage must not cover redirected combat damage, because the potential amount of redirected damage is simply too high.
Also, the reason why Rite of Rage is so cheap is because it requires prediction, like Fiery Resolve. If you use it but no non–combat damage happens, it's a dead draw, but cheap. Redirecting combat damage requires no prediction as you are the one redirecting it, and thus becomes dirt cheap for what it does.
Solution 1: Code redirected combat damage as 'combat damage' rather than 'non–combat damage'.
Solution 2: Change the card's functionality and text to cover non–combat damage from character/artifact/location/mission abilities and ability cards only. This might cause confusion and be impractical, so I prefer the above solution.