To the 1 that was asking if onyxia was 1 of the dragons that enchanted the world tree, here is the right info:

Alexstrasza, the Lifebinder, placed a single, enchanted acorn within the heart of the Well of Eternity.
Nozdormu, the Timeless, placed an enchantment upon the World Tree
Ysera, the Dreamer, also placed an enchantment upon the World Tree by linking it to her own realm, the ethereal dimension known as the Emerald Dream

Onyxia is not 1 of them.