give your self command block:

/give @p minecraft:command_block


summon FallingSand ~ ~2 ~ {Time:1,Block:command_block,Data:3,TileEntityData:{Command:gamerule commandBlockOutput false,auto:1b},Passengers:[{id:FallingSand,Time:1,Block:command_block,Data:3,TileEntityData:{Command:fill ~ ~ ~ ~ ~-2 ~ air 0 replace,auto:1b},Passengers:{id:FallingSand,Time:1,Block:repeating_command_block,Data:1,TileEntityData:{Command:execute @e[type=Snowball] ~ ~ ~ kill @e[tag=tracker,r=3],auto:1b},Passengers:[{id:FallingSand,Time:1,Block:chain_command_block,Data:1,TileEntityData:{Command:execute @etag=tracker] ~ ~ ~ summon PrimedTnt ~ ~ ~ {Fuse:0}},Passengers:[{id:FallingSand,Time:1,Block:chain_command_block,Data:1,TileEntityData:{Command:kill @etag=tracker]},Passengers:[{id:FallingSand,Time:1,Block:chain_command_block,Data:1,TileEntityData:{Command:execute @etype=Snowball] ~ ~ ~ summon AreaEffectCloud ~ ~ ~ {Duration:2,Tags:[tracker]}}}]}]}]}]}]}

after pasting this command put a redstone in the sideof command block