My guild discovered this exploit last night during one of our Sindragosa 25 attempts. A holy priest with the Spirit of Redemption talent can get an ice block, let it kill them, and bug it out once they enter spirit form. The block will remain there even after the person inside leaves spirit form. To exploit this bug, use it as a free wall to ALWAYS line of sight the Blistering Cold and/or stacking debuff in Phase 3.
After noticing the bug, we repeated it by sending our entire raid in and pushing Sindragos to her air phase. We made one of the marked players stack with our priest at a convenient place to have a free ice block. After the players died, the priest's ice block still remained, and we wiped it up to have all 25 people alive. We came back in for the kill with our ice block still there for help during ALL of our phases:
Phase 1 - Sent laggy users or those that suck at running out to sit behind the ice block 5 seconds before Blistering Cold so they wouldn't be pulled and would have a short distance to run out.
Phase 2 - Free ice block to LoS behind that didn't have to be killed.
Phase 3 - We positioned all of our healers so they could safely heal our raid from behind the special ice block, where they got NO stacks of the debuff (besides when they rotated out to heal tanks)
All in all this exploit has limitless opportunities. You could draw yourself a smiley face of ice blocks on the floor as long as you can convince your priest to die that much. Enjoy.