Minecraft wiki entry for Defense, associated text: Like historical defensive formations, the most secure perimeters are based around multiple concentric systems used in synergistic combination. A classic example is a moat surrounding a walled compound - creatures which might reach and breach the wall (e.g., endermen) are delayed or killed before they can reach the wall by the moat (water or lava). Any and all of the aforementioned passive defensive measures can be used to make an area secure; the only limit is the amount of time the player is willing to put into it at the expense of other goals and the amount of space and time available.