Minecraft wiki entry for Combat, associated text: Dispense lava: A dispenser loaded with a lava bucket can act as a powerful area denial tool as it creates an extremely harmful hazard that will make short work of any mob that runs into it. Dispensing lava to attack the foes is slightly more efficient than placing it as the dispenser allows the player to maintain a safe distance between the player and the lava to avoid burning themselves and the dispenser can also suck up the lava without problems, making it a much safer alternative to placing lava by hand.