Err not exactly a hard question, From all the klaxxi she was gripped with all out paranoia / Wanting to eradicate every single thing because they would ''conquer'' her people example within the phase of the empress the sha goes
''They have to conquer your people empress! Destroy them!''
It's sort of like how when the Sha of Anger spawns, all of the mobs near it become enraged. Just being near a Sha is enough to affect things. The Sha of Fear was inside the Heart of Fear with the Empress, inside her chambers, until she died, so it's likely that his very presence is what terrified her.
I think the Sha feed off and amplify x1000 already pre-existing emotions
This is pretty much correct as the lore states. Those who can control their emotions can suppress the Sha, however even Taran Zhu couldn't do this when his hatred welled up seeing us bring our war to his domain.