Daemon Engine of Tzeentch - Mirrorfiend

"The monstrosity that pushed its way between two warehouses stripped to bare ferrocrete was neither living nor machine but a wyrd-cursed amalgam. Its six many-jointed legs carried a flattened body from which protruded long growths with puckered openings at the top. Metallic plates grew from unnatural flesh, glinting with heretical runework. Warpfire flickered from the body-tubes, leaving trails of multicoloured exhaust fume. Its head was like that of a giant beetle, many-pronged antlers of black and red like a phalanx of spears thrust from the top"
Thorpe, 'Ashes of Prospero'

There are a number of hints across 40K lore of a special daemon engine of Tzeentch that looks like a beetle, sort off. It should have its own rules but can be played as a Forgefiend with ectoplasma cannons and jaws.

This particular model is a Bob Olley sculpt sold by Reaper as a Giant Beetle in metal, and is slightly small for a daemon engine but not outrageously so - given that a mirrorfiend is described elsewhere as 'slightly smaller than a battle tank'.

Mierce Miniatures make a bigger sculpt that would be even more suitable but is inevitably more expensive, around £40.