The new achievements coming to Halo 4 with the Crimson Map Pack on December 10th have been revealed on :
Now They Fly? – Get a kill while airborne in a Warthog. – 50 points
Size Is Everything – Kill 20 enemies with a detached Machine Gun Turret. – 20 points
ODST – Kill a player while you’re airborne from using a Man Cannon. – 30 points
Bigfoot – Kill 20 enemies using the Mantis’ stomp attack. – 20 points
David and Goliath – Board an enemy Mantis. – 20 points
Clay Pigeon – Shoot an enemy out of the air while they use the Man Cannon. – 40 points
Special Delivery – Kill an enemy with a melee attack when landing from a Man Cannon. – 30 points
Pump Yer Brakes – Score the killing blow on a Mantis. – 40 points