Kill 10 monsters with one mine [15G]

A great place to get explosive mines is on the rooftop of the "Old Town Cinema" in Henderson. They will keep respawning in chapter 13, so you can farm as many as you want.

Once you have an explosive mine, go to the Ferry Station. Gather up a group of 10 zombies and jump on a car so they cannot hit you. Just shoot around to get their attention. Wait until 10 zombies are in one spot and start killing them. You may not dismember them with bladed weapons! Use guns or blunt weapons, their bodies have to stay intact. Leave one zombie alive and let it trigger the mine. The explosion has to destroy 10 bodies, no matter if these bodies are alive or dead. Of course you can also plant the mine while the ten zombies are still moving, but the blast might not destroy all bodies. It's safer to kill them first.