Terms searched for:
"Priest"
"Levitate"
"ToC25"
"Gormok"
If this has been posted before and knocked off the search filter then I apologise for the repost.
The idea behind this "clever use of game mechanics" is simple. Basically, the first boss of the Northrend Beasts encounters will cause patches of fire to spawn on a player via the abilities of the adds he introduces into the encounter - the Snobold Vassals. Normally, these Fire Bombs deal direct damage in the region of 5.1k health and leave a flame patch that damages those that stand in it. Additionally these patches also apply a rather heavy hitting DoT that stacks on those that bathe in the yummy flames for too long.
However, if a player with Levitate is hit with a Fire Bomb they will only take the direct damage of the strike and will not cause a flame patch to spawn nor will they receive the DoT. This can help decrease the damage the raid takes and allow for more time and healing resources to be devoted to the tanks who can take rather large spike damage.
Personally, I would not recommend re-applying Levitate during the fight due to waste GCDs but the exploit may be of some use to the raiders amongst yourselves especially on the Grand Crusader trial due to the heavy spike damage on the tanks.
I will attempt to get a hold of some screenshots tonight. Again, apologies if this is a repost and any moderators are welcome to delete if this is the case.