The Eidolon Midgardsormer, The Serpent

One of the three legendary beings, known as The Eidolons, creatures left behind after the Catastrophe by the Prime Dieties to safeguard the mortal realm.
The true size of this Eidolon is yet unknown, as it has never fully surfaced, keeping the potential bulk of its mass beneath the surface. It is said to be able to swim through stone and earth as if a fish through water. There is almost no way to track its movements, as it disturbs nothing in its passage, other than granting a wave of vitality, easiest seen in abrupt plant growth. 
Its head is protected by a layer of diamond, helm-like in nature, and inside its cobra-esque hood, two massive rubies stare out like the eyes of an even larger beast. Its scales look largely to be made of raw ore, and the life energy it radiates heals whatever can penetrate its hide in seconds. Massive jade-colored eyes seek to paralyze its foes, or at least distract them from the bite from its venomous platinum fangs. The earth roils in its presence, wherein unwitting foes may find themselves pulled deep into and entombed for later consumption.

Ball of Wild Earth  Adamantoise