Plague / Epidemic
The few Eladrin colonies able to plant the Seeds given to them by Gaia herself, saw themselves overwhelmed by giant, ever-hungry trees that drained the life of the land around them.
These Seeds grew into giant trees that spread blight, and death around them as they drained the life of the continent itself, turning its nature from one originated of the God of Order, into that of one loyal to Gaia. Some colonies, after witnessing what these Trees caused, decided to do seal them, against the orders of Gaia. This lead to the extinction of most of tried. Regardless, Gaia gained a foothold in the Eastern Continent, even if barely more than just an observing one.