This sandstone based tower is a relatively safe tool for starring down endermen and killing them from the ground floor. The structure will be build 1 block to the east and 1 to the north of the command block. The command block will be on top of the 'groundlevel' and it is nescessary to have 8 block of level terrain to the north of the command block. The tower has and observation deck, a battledeck (for surrounding mobs) and the ground level for killing the endermen. I suggest to add cactus around to fend of spiders and some torches to reduce treats.