The Slumbering Tsar
A massive block of stone rolls ponderously toward you on great stone rollers. Iron plates armor this stone monstrosity, the front of which is studded with spikes of iron, adamantine and stone. Great stone clubs capped in iron sprout from loopholes in the sides like the arms of a giant. The top of this huge structure is a platform surrounded by stone merlons to provide cover for any defenders riding upon it. At the back edge of this platform extend two chains that end in great stone spheres that spin on a pivoted base and lay waste to anyone behind the mobile fortress.