Nalak, The Storm Lord
When Lei Shen discovered a rare clutch of thundering cloud serpents, he was awed, and set to subjugating them. The largest hatchling fiercely resisted, and when Lei Shen visited the handling pens, he laughed mightily at the charred mogu that lined the walls. He took the hatchling for his own, and for its obedience, granted it power over the storms and the sky. For thousands of years following the death of the Thunder King, Nalak has guarded the walls of his hidden citadel, awaiting his return.
more detail please check:http://eu.battle.net/wow/en/game/patch-notes/under-dev/5-2/nalak