Vallorn
The Vallorn... nothing less than the vile offspring spewed out from the mating of a Great White Shark and a rampant fungal infection.
Zietel van Temeschwar, MountebankA Vallorn is a malignant hostile magical ecosystem. At this time the Vallorns are for the most part quiescent; however, when enraged, they spread quickly and cover everything in their path.
There are monstrous plants inside the area, the spores of which mutate living creatures that are exposed over many months. They are mostly sessile and threaten only the people who come near them. The air itself is different in the area of a Vallorn, weakening those who enter as if they were breathing mild poison.
The Vallorns appear in more than one place - around each of the Navarr cities - and in some way each centre of Vallorn activity is connected to every other.
There is no intellect behind the Vallorns - they are not self-aware. They will strike back if damaged or hurt, much as a beehive or ant's nest will use its footsoldiers to drive off the invader.
We welcomed the night; in the darkness we could not bear witness to the Vallorn’s appetite. By day… by day all Its wants, Its passions, Its yearnings were laid out in their visceral horrors. Synod forgive me for I know the Law cannot; but when darling Arturo came back to me – mud in his veins and thorns in his mouth – and he gestured me to embrace him… I ran, and I ran, and I ran.
Cai, Thorn of the Conclave, after the reconquest of Miaren prior to his execution for desertionThe Vallorns have not spread since their creation - but that's not to say that they couldn't if conditions were right, and the Steadings take great pains to ensure they are not disturbed until the time is right. They also regenerate so fast that it's unfeasible to destroy them with axes or fire. Attempts to do so in the past have been doomed to failure.
A Vallorn is dangerous in the way that a sleeping lion is. If you stay away, it can't hurt you directly. Poke it with sticks and trouble is coming your way. What complicates the matter is that the Vallorns also produce monstrous, eerie insect horrors that leave the area they controls and voraciously attack communities that live nearby.
What is known is that with the Empire in its weakened state, an attack on any of the Vallorn would certainly be disastrous.