I actually kill them pretty often. I probably kill asbout 30% of all metal king slimes I encounter. It's because I have thunder thrust under the hero's spear skills, and executioner under Yangus's axe skills. Liquid metal slimes, about 40% and metal slimes, about 60%.
Good bye everyone, it's been fun!
Special thanks to ED_, superman4u, and Cross Stinger
Credit for the Siggy goes to shadow slayer