Mobs In Grass!
Walk into some Tall Grass and possibly encounter a mob!
(5% chance of seeing a mob)
You can battle a zombie,skeleton,creeper, cave spider, iron golem, endemran, and Giant!
/repel: If you hold 10 redstone and type /repel, you will have a .05% chance of encountering mobs for 15 ticks
/attract: IF you hold 10 glowstone and type /attract, you will have a 10% chance of encountering mos for 15 ticks.