When an environment that holds several powerful spirits becomes blighted and so far gone that it will soon collapse, sometimes these spirits will coalesce and manifest in a physical form, taking things from the environment such as fallen trees, rocks, as well as dead plant and animal life.

The new "elemental" will hunt down and destroy those that it views as responsible for the injustice done against its home, and though it is slow, it can hardly be stopped, towering 12 to 26 feet tall and weighing up to 15 tons.

It can resist even the strongest of fires for up to an hours at a time, the flames sometimes even being taken into itself and used against those trying to stop it.

I've had a few Mythos like ideas floating through my thoughts lately.