Ogab'd-pattern anti-aircraft Wraith
From Halopedia, the Halo wiki
The Unknown Wraith is a new variant of the Wraith tank in use with the Covenant armed forces.
Appearance
It is near identical to the original Wraith tank in appearance, par its top canopy and mortar. Instead of a mortar it mounts a frame that seems to hold either two plasma cannons or Fuel Rod Guns that fire a series of slow moving green plasma blobs in a rapid succesion. It appears to be an anti aircraft variant for assault the many UNSC Hornets in the area where it was first seen.
Sources
http://uk.media.xbox360.ign.com/media/734/734817/vids_1.html
