Troll

/summon MinecartCommandBlock ~ ~1 ~ {Time:1,Command:summon FallingSand ~ ~5 ~ {Block:redstone_block,Time:1,Riding:{id:FallingSand,Block:command_block,Time:1,TileEntityData:{Command:fill ~ ~1 ~ ~ ~-3 ~ air}}},Riding:{id:MinecartCommandBlock,Time:1,Command:/setblock ~ ~1 ~ stone,Riding:{id:MinecartCommandBlock,Time:1,Command:/setblock ~5 ~1 ~ redstone_block,Riding:{id:MinecartCommandBlock,Time:1,Command:/setblock ~4 ~1 ~ command_block 1 0 {Command:/tp @a ~ -1 ~},Riding:{id:MinecartCommandBlock,Time:1,Command:/setblock ~5 ~2 ~ command_block 1 0 {Command:setblock ~ ~-1 ~ redstone_block},Riding:{id:MinecartCommandBlock,Time:1,Command:/setblock ~5 ~ ~ command_block 1 0 {Command:setblock ~ ~1 ~ air},Riding:{id:MinecartCommandBlock,Time:1,Command:/kill @e[type=MinecartCommandBlock],Riding:{id:FallingSand,Block:activator_rail,Time:1,Riding:{id:FallingSand,Block:redstone_block,Time:1}}}}}}}}}