Mana Alteration was one of the lost techniques. While it wasn't that much effective normally, yet it possessed a greater threat to Niondra as its very core could be shattered only by Mana Alteration.
Since it required consistent mana supply for stabilizing the floating capital at its state, a small amount of disturbance in the mana flow, could cause a massive amount of causality.
Skyler's 'Disintegrate' and 'Scavenge' skills were not entirely a mana alteration technique, but it was made on the very principality. Using them inside El Niora, could trigger the disturbance which could furtherly rise the concerns of the Sovereigns. Though he wasn't aware of the fact.
As Arnol left the council meeting hall, the situation grew tensed. An alarming threat was before the Sovereigns. Yet, they couldn't possibly do anything but to argue over it. Soon a debate took place.