|Drawing of a Ping Kuang Bu Zhan Sui Di Gun, from 'Wu Bei Zhi (《武備志》)'.|
Ping Kuang Bu Zhan Sui Di Gun is a cylindrical tree trunk full of poisoned blades, hooks and nails. To propel/roll the tree trunk forward, it is mounted with sixty linked black powder rocket propellers, which also double as short range flamethrowers. The tree trunk is also hollowed out and filled with explosives and blinding dust, and will explodes into a shower of flaming wood splinters, smoke and blinding dust after a predetermined time.
Despite being such a strange weapon, the idea of using explosive rolling cylinder as weapon was apparently not unique to the Chinese, as evidenced with this similar German design, pictured below:
|A German flaming/explosive tree trunk. Image taken from 'Ms. Codex 109', also known as 'Feuer Buech'.|