Kneel Before Z... is a trophy in Uncharted 2: Among Thieves.
It is awarded when the player gets 5 Put 'Em Down medals. It only becomes available after the Siege Expansion Pack has been downloaded and is not retroactive. As it is part of a DLC pack, it is not required to earn the Uncharted 2 platinum trophy. It is likely a reference to the famous line "Kneel before Zod!" from Superman II.