In this post, i will be showing you a beta 1.4 (with a beta 1.6 fix) mob system. the mob farm is a 30x30 4 block high mob farm with 16 6x6 spawning pads. As you can see there are gaps between the spawning pads where there is water. This is to push mobs up to the center where there is a mob elevator. This four way mob elevator makes the mobs swim up to the spider separator and mob killing areas. As you can see there the 2 block tall mobs swim up the mob elevator (going through my base) and the spiders go die a horrible death. After that the creepers, zombies and skeletons get sent to a mob grinder area. That is all! If you have any questions post them below and i will answer them.