So, something I just found out yesterday:Mirror Image got a massive nerf when it came to KMS, or maybe even during KMST itself.
Regardless of when it happened, Mirror Image's hits are 60% off the DB's normal attack range, not 60% off the skill damages.
Second thing is...Mirror Image hits don't activate Thorns. With both of those nerfs, DB's aren't as strong as previously thought. =D