Rextroy recently released a new video where he utilizes 
Flash of Light and 
Blessing of Summer to destroy Horde players!
How Does The Bug Work?
The combo is built around a NPC in Durotar named Zunta. What makes it so special? Zunta can be healed by Alliance players for a massive amount, thanks to scaling when healing lower-level targets.
Blessing of Summer turns healing into damage, but this usually doesn’t include scaled healing. However, by using 
Selfless Healer, Rextroy’s healing counts toward Blessing of Summer.
For each Flash of Light he performs, Rextroy deals damage equal to 20% of his health, as Summer has a 20% cap per proc, and a 1-second cooldown in between casts.
Rextroy decided to switch to Protection, since the spec has access to more health increases and a higher output of Flash of Light and had another player cast Summer on him. The combo can be performed solo, but keep in mind Holy spec is more limited in damage output (3 million versus 4.5).
The final part of the combo was kiting and baiting Horde to the sacred ground!
See The Combo in Action!
Watch Rextroy’s latest video here: