Apex (Part 1)
Due to the influence of the World Tree over the world energy, mana organs could only process it with extreme difficulty. It even resisted the pull from the mana cores when Awakened used their breathing technique and the attempts to mix world energy with pure mana to conjure any form of magic.
Only Spirit Magic was immune to such effects but it was mana expensive and recovering with Invigoration took longer than usual.
Those near Nandi and Lith didn't suffer from the Yggdrasill's influence, the world energy surrounding them was purified respectively by the bio-crystals and the Apprentice Hands, but they numbered too few to matter.
The arrival of more greeds of fresh Wyrms just prolonged the time the World Tree would need to get rid of the pests swarming their dominion.
Yet that only applied as long as the world energy was under the Yggdrasill's control.