The body isnt anything special, but converting a Clue, or even an Arabella, into damage later on is a big upside
Its best paired with blue partners like Sakashima of a Thousand Faces, as being UR gives you access to other coin flipping cards like Okaun, Eye of Chaos and Zndrsplt, Eye of Wisdom
It has one Move that does a whopping 1000 damage
Without much to go by since his ability depends on the contents of the Necron deck or perhaps a monoblack Vehicles deck, we couldn't see much of an opening to use Szarekh as the commander of his own Warhammer 40,000 deck, but, at least at this present moment, we could see him working well in a deck led by Greasefang, Okiba Boss from Kamigawa: Neon Dynasty
[1] There are two exceptions: Draft formats (like Cube, or Limited) can have 4-16 players