This is a fan concept of thunderclast from Brandon Sanderson’s novel Stormlight Archive.
In the novel a thunderclast is created directly out of the ground by a void spren inserting itself into the ground. It is characterized by arrowhead shape head, a skeletal body, and hate and menace.
This is how I imagine a thunderclast might look if the battleground is in the arctics, or on ice-capped summits. The lifeless frozen fields will be great for javelin throwing attacks. The glyph says ‘himonas’, meaning winter. I also took inspiration from Mark Lawrence's Book of the Ancestors trilogy, where he described black ice threading through glacial ice as conduit for evil. I thought that would be cool to have black veins visible running throughout the body of an ice thunderclast.