I hadn't found similar topics (except http://www.ownedcore.com/forums/worl...g-exploit.html (Madness of Deathwing Exploit) but it shows another mechanic) if they exist pls delete this one.
So yesterday while making pull of deathwing in 25 heroic difficulty, our warrior disconnected on the brink of a platform - raid jumped on another one when big tentacle appeared - it aoe hit only warrior whose character stood on another platform.
Today I went there in lfr 25 difficulty and checked it by my mage - it works - 100% chance that aoe ability of tentacle hit person on nearest platform
so you need to:
1) pull the boss
2) wait until big tentacle appear
3) one person jump from your current platform to another one (which is closer to tentacle)
4) only person who jumped from your platform will take damage
here is video (is short - if anybody didn't understand what to do, and how , i can fraps whole fight):
[Expoit] Madness of Deathwing - avoid tentacle splash damage - YouTube