(I'll be posting pictures after tonights Vezax raid. But this does work as I tested it the week beforehand)
If your a caster dps class, the shadow crash effect on the floor buffs you to require 70% less mana per cast, and alot of haste + bonus damage. The buff from this is pretty huge.
However the debuff only fades when you manually leave the edge of the shadow crash graphic on the floor. So if you DC/Close wow/leave game in any other manner, while in the shadow crash, you are still buffed, untill entering and leaving another shadow crash.
So to sum this up
1.Genral Vezax fires a shadow crash
2.Walk into the shadow crash and get the buff
3.DC/Close wow/leave game somehow.
4.Log back in after the shadow crash graphic has dissapeared from the spot you dc'ed in
5.Continue to have the buff till you die/walk into another shadow crash and back out.
This can make both general Vezax, Yogg saron, and the iron council (if you leave it up, before heading to the watchers) fairly trivial, even in hard modes.