The fight itself isnt hard, but getting all things together took hours. Tried to get goblin invasion also, but they didnt spawn and I think goblins cancel ordinary mobs. So I opted for Blood Moon and that together with my custom corruption made it abit more fun :)
I dont consider this skill in any way, cause I take very little damage. This is made to entertain and not to show how-to och guide you to a kill.
King Slime proved to be a problem to get to spawn, but once he spawned I put him in a cage and he never despawned. Also did this 2 times, because Eater of World despawned one time - horray! Thats why Im fighting just by the corruption area.