Location: Forest clearing, or towering over some treetops
Action: This is a mega-huge, fantasy pachyderm -- the lord of all the hugest mammals. Show it as a sort of cross between a rhino and an elephant -- tusks, nose horn(s), plates of armor, and thick round feet -- charging aggressively or rearing back over the treetops. It's definitely a fantasy creature -- perhaps it has six spiraling tusks, or a clawed trunk, or a partially bipedal stance.
Focus: The pachyderm-lord
Mood: Ultimate strength, ferocity, and destructiveness
And here's the sketch Lars turned in. You also get to see what Terastodon was called at that point in the process!
The creative team liked the direction and gave the go-ahead. Here's the final version, as seen in packs of Worldwake.