Tales of Tolgard
Elementals of nature are enigmatic beings summoned from an unknown plane to demolish all signs of a settled area and return it to a state untouched by civilization. A summoned nature elemental does its task for 24 hours or until an area with a one-mile radius has be remolded. The summoned nature elemental destroys any nearby buildings, man-made structures, and even humanoid life. The only exception from this is the summoner and they people they designate upon summoning.
These elementals appear as monstrously huge (at least 35 feet tall) composites of the natural substances of where it was summoned. A nature elemental represents the combination of all the elements of nature: earth, air, fire, water, and what some say is life.
A nature elemental destroys any and all signs of civilization and humanoid life in the area until its task is complete. With no opponents, it simply flattens an area and remakes it into a pristine natural habitat. When faced it combat, a nature elemental employs its powerful fists to destroy interlopers.
A nature elemental remolds its target area around it to become a bastion of nature. The soil becomes fertile and new plants grow. New animals feel mystically drawn to the area. Any unattended objects that are trampled or smashed by the nature elemental are destroyed and assimilated into the remade locale.
As long as a nature elemental has contact with any of the elements (air, earth, fire, or water), it heals all damage to it after every exchange of blows, even replacing lost limbs, unless it can be killed in one round. If the elemental can be somehow separated from all of all of the elements (like being trapped inside a vacuum), it will not be able to regenerate.