Mob Grinder

Multiblock that automatically kills mobs funnelled into it.

Structure

Layer	Block
Top	Dispenser (facing down, loaded with arrows)
Middle	Fence (2 blocks tall, mob funnel)
Bottom	Hopper feeding into Chest

Passive. Mobs pushed through the fence funnel into the Dispenser's line of fire are killed automatically. Drops collect in the Chest via Hopper. Requires a mob-pushing mechanism (water stream or cactus/soul sand funnel).