It's unusual design is because it is a grav tank built to approach its targets silently and with utmost stealth, it is deliberately made to be a thing of mystery and terror when its presence is unveiled. Used primarily in a paramilitary role by the Sisters of Silence, it can suppress civilian resistance with lethal effect and this translates well on to the battlefields of the Horus Heresy.
Lyden P did a great job on the heat bloom from the exhaust jets.
It is armed with Hellion Cannons, basically buffed shorter range Autocannons for cutting through rampaging mobs and destroying makeshift barricades. Against greater threats, it's fitted with Missile Launchers armed with various payloads of missiles, including sophisticated antipsyker warheads.
Cheers for checking it out, thanks, Siph. (1 point for the base)