Hex ruin would be fine if it didn't had a stop in progress.
The whole idea of ruin is fine, the loss of 5% progress is ok if it didn't have that additional stop in progress after hitting the skillcheck. That actually resumes in a loss of more that 5%. Not to mention that progress stop also affects you when someone else hits a skillcheck.
If right after hitting the skillcheck and losing 5%, the progress just continues as normal then this perk would be more balanced.