"In the depths of the eye of terror, on those worlds bound in blood, demon and machine have become fused, cohabiting the same metal shell. These lumbering metal behemoths act as warp conduits, summoning warriors and demons from across the stars into battle. The Demon inside the tank acting as the general of its infernal force.
A Demonica Class Land Raider is a fearsome sight to behold on the rare occasion that it can step from the warp. It stands as a war alter to Khorne. Unlike even other demon possessed tanks, the Demonica has no interior troop transport, it is instead filled with a powerful greater demon of Khorne. Through the Demon's power the vehicle becomes a conduit for warp travel, allowing troops to assault directly into battle from the ships above, or even other warp shrouded planets. Although such travel is risky and takes up most of the demons power, so it can only be done rarely. The demonic energy does allow bloodletters to survive in close proximity to the greater demon, often riding along the hull, cutting down those who get too close the the might tank."
Some of you may remember this piece of artwork that I did quite a while ago: