Jan Žižka's Wagenburg Wagons

Origin
Jan Žižka was a Czech general from Bohemia who fought against the Teutonic Order, rebelling Bohemians and the armies of Hungary and the Holy Roman Empire. Žižka's tactics were unorthodox and innovative. In addition to training and equipping his army according to their abilities, he used armored wagons (known as wagenburgs or laager) armed with small cannons and muskets, presaging the tank of five hundred years later. He was also a master at using geography to full advantage as well as managing the discipline of his troops. Žižka is considered to be among the greatest military leaders and innovators of all time and is one of several commanders in history who never lost a battle.

Effects
Each wagon is activated when a weapon, preferably a firearm, is onboard. The wagons become unstoppable tanks, attacking anything in sight. They will unleash artillery and other projectiles capable of breaking wood and stone and heavily damaging modern materials. Luckily, their range is restricted to about 30 meters in any given direction.