Leviathan...that sounds like an interesting strat. One I hope that Blizz don't 'hotfix' but a valid one all the same. Just to get things straight:
1. Ranged and healers don't move at all for the whole fight and stay on the ledge?
2. How far back from the ledge is the MT tanking him? And I am guessing your OT just hags with the melee and roots the golems as they join?
3. Do the golems head straight for the middle of the pool to get around? ie. through the centre sections?
Might give this a try. Sounds crazy easy, and the fact it's a sloped ledge.....hmmm.
More freaking plate drops then a Greek Wedding...