I have some thoughts about the differences and similarities between Nature and Plague:

• In my mind Plague flight healers don't just wait and see if their patients survive without help (rude). Instead they will inoculate their hatchlings with small doses of diseases early in order to build up immunity, and take pride in having kick-butt scars. Prosthetics imported from Lightning and Wind (patchwork wings) are in high demand for those who can afford them.
• Nature healers are more about concocting herbal medicines (potions, balms, and poultices) and making sure wounds disappear completely. Very skilled at stitches and can even encourage limbs to grow back or be replaced with symbiotic plant matter.
• The Behemoth is a superorganism with roots that stretch through the entire Viridian Labyrinth. This is kinda supported by the world map, but I'd like to take a step further and propose that most of the trees in Nature territory are the Behemoth's suckers. They're all connected as a single organism via the roots, like the Trembling Giant forest in Colorado, USA. Bladed Flatleaves come grow from it seasonally, and the One Seed is a very rare fruiting body of the Behemoth.
• Likewise, Plague has its own superorganism in the form of an enourmous, underground fungal colony, similar to Oregon, USA's "Humongous Fungus." It spreads through the sand and soil, turning it red, and grows up into plants and kills them for nutrients. The All-Seeing Shrooms are actually the fungus's fruiting bodies, which grow seasonally. Of course because it's a magical fungus it can also grow the occasional eye or weird claw.