Why is this not a thing in 40K? We've got snipers, drug-fueled rage machines, shape-changers, anti-psykers, poisoners, and infocytes. Psykers are an integral part of what makes 40K so awesome. So how is it nobody has ever come up with an Officio Assassinorum Temple of Psykers who can mentally dominate a target or throw them off a ledge with telekinesis?