Ok so basic story is a leak has broken out on Azeroth and all our characters have to go stop the leak.
New Class. Plumber.
New Profession. Sewer Manager.
One raid. Leakfall Tides.
Seven new Dungeons that end with your character having to fix a broken leak.
Main antagonist of xpac is called Leaky McLeakface.
Hogger is also a raid boss. He has a leaky cauldron that we need to fix.
Leaks......
(Figured since everyone else was doing it I'd have a really poor go at a leaked xpac)