You must be in the Renaissance path and have the University and Rocketry upgrades. The Logistics upgrade in the warehouse is also good. Enable the makemenails code (and also the gimmegimme code if you are low on resources). Produce three to five Sappers. Build as many Rocket Launchers as you want and one Supply Wagon for every three launchers. Make the wagons follow different launchers and send them to attack your enemy's manor. They will be invincible and kill all units around the target.
You must be the pagan and be stuck of money or materials. Build a "Temple Of The Moon", then build an Arch Druid. Go up to a gold or stone mine and create a Gold or Stone Elemental , then kill the Gold or Stone Elemental. This will leave 10 to 15 bits of gold or material on the floor. Repeat the process until you have between 200 to 300 pieces of gold or material on the floor. Send a group of peasants over the gold or stone and get them to collect it.
Do not forget to use the Lucky Wagons. An easy way to find them to enable the doyousee code. Then on the mini-map, click on the "Toggle Resources" button. This will leave you with your town and the enemies colors on the map as well as some black dots. Go and look at the black dots. If the Lucky Wagon is there, send a Knight or the nearest unit the wagon. Even after reaching the population limit, it will still allow you to use them.