The Son Of Cenarius

There is only one being in the history of Azeroth that fits the description of what you experienced - the Wild God Malorne, the Waywatcher. He was ancient when this world was young, one of the primal guardians roaming the untamed wilds years before the Sundering. His immense power and prideful presence strikes fear into his enemies and comrades alike, yet his loving way of fostering nature made him revered with the latter.

What you experienced is horrid. To think the Nightmare might have taken a hold on even a fragment of the great Malorne is terrifying. We must act immediately. <name>, while I send notice to Moonglade, I need you to gather twenty bright dream shards. They are imperative to shield you against the Nightmare's grasp. Assist us in our cause, scour the hills of Hyjal. However you acquire them, do it quickly!

Once you have them all, bring them to Keeper Remulos in Moonglade. He will give you further instructions.

<name>! Arch Druid Dreamwind informed me about what transpired on Mount Hyjal. Do you have the dream shards with you?

Well done, <class>. Seeing you complete this task so quickly reassures me to not be doubtful of what I will be asking of you. You may be unaware, but my brethren and I are Malorne's scions. It was his union with the Moon Goddess Elune that bore life to our father Cenarius - and he in turn created us. This is not only a concern for the safety of Mount Hyjal or even to my family, but also to all of Azeroth.