OK, it's quite obvious this close up that it's a Chaos Space Marine commander painted with metallic colours. You'll just have to take my word for it that he's a Necron Lord. In HOTT terms he is a Cleric.
The army looks like it's supposed to from two feet away, which is the distance most people will see it at on the table
Behind him is the brooding presence of an Abattoir; an Airboat in HOTT*
*And, yes, that's not strictly correct according to the semi-official Games Workshop fluff. But I'm free to make up bits I want to here. So there.