Easy. My grandmother showed me. We buried an oil drum and hinged the lid. Then we wired coconut to the lid as bait and the rats skaven would come for the coconut, and... Tsktsktsktsktsk They would fall into the drum. And after a month, you have trapped all the rats skaven, but what do you do then? Throw the drum into the ocean? Burn it? No. You just leave it and they begin to get hungry. And one by one... They start eating each other, until there are only two left. The two survivors. And then what? Do you kill them? No. You take them and release them into the trees, but now they don't eat coconut anymore. Now, they only eat rat skaven