THIS piece sure brings back memories. I was still on staff at WOTC as a concept artist, and in line with my self-made title of Tree Boy I was given the task of developing the island of Yavimaya from the ground up. Yavimaya was supposed to have a Gaia-like, magical sentience. Assisted by the elvish population on the island, Yavimaya was the place on Dominaria where resistance to the Phyrexian invasion would be fiercest (as I imagined things). Yavimaya had grown herself a gigantic arsenal of vegetal, insect and animal weaponry to repel any invaders. Those huge arches going out into the ocean? Think of a tree with the body structure and musculature of a reticulated python. Phrexian machines wading ashore were summarily wrapped up and crushed.
I never had the opportunity to read the novels but in my mind, Yavimaya never got conquered.