Originally Posted by
WolfRider
We don't find "Light's Heart", we receive Xe'ra's Core that was sent by Turalyon from Argus through the Portal in the Tomb Of Sargeras.
We don't need Xe'ra's ancestor (because Xe'ra is one of the Elder Naaru) to communicate with it, we need a compatible receiver for the core to make the communication possible.
Xe'ra is not killed by Rakeesh, it's O'ros, the Naaru that was guiding the Exodar to Azeroth. Xo'ros wasn't killed, it was weakened and turned to a Void Bomb by Rakeesh.
Velen doesn't turn "emo" and he's not lost. Velen is an oracle, an oracle doesn't interact in life, he tells the vision and tries to find a meaning. The reason he changed is mind is the following : he foresaw the death of his son long before he came to Azeroth, but he never knew if it had already happen because his son was taken by Kil'Jaeden after he fleed from Argus. So he had to make his veil while he was saving his people.
And while we are fighting Rakeesh, he realises that this vision was happening and he could change his son's fate.
He realised that being an oracle was bullshit and that if he acted sooner, things would be completely different and a lot of life could have been saved.
He realised that when the Army of the Light led by Naaru came to him on Draenor he should have join their fight.
That's why from this event, he decides to fight back and go to Argus.