Random Head Generation! Just change the SkullOwner or Data!

/summon FallingSand ~ ~1 ~ {Block:redstone_block,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/fill ~ ~0 ~1 ~ ~-13 ~1 redstone_block},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:setblock ~ ~3 ~1 stone},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:setblock ~ ~4 ~ command_block 0 replace {Command:fill ~ ~2 ~ ~ ~-17 ~1 air}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:setblock ~3 ~-10 ~-1 command_block 0 replace {Command:execute @e[type=Chicken,name=Test] ~ ~ ~ spreadplayers ~ ~ 1 120 false @e[type=Chicken,name=Test]}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:setblock ~3 ~-9 ~1 command_block 0 replace {Command:scoreboard objectives add kill dummy}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:setblock ~4 ~-8 ~-1 command_block 0 replace {Command:scoreboard players add @e[type=Chicken,name=Test] kill 1}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:setblock ~4 ~-7 ~1 command_block 0 replace {Command:execute @e[type=Chicken,name=Test] ~ ~ ~ fill ~ ~-1 ~ ~ ~-1 ~ air 0 replace minecraft:command_block}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:setblock ~5 ~-6 ~-1 command_block 0 replace {Command:execute @e[type=Chicken,name=Test] ~ ~ ~ /setblock ~ ~ ~ minecraft:skull 1 keep {ExtraType:LapisUniverse,SkullType:3,Rot:-8}}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:setblock ~5 ~-5 ~1 command_block 0 replace {Command:kill @e[score_kill=2600,score_kill_min=2600]}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:setblock ~6 ~-4 ~-1 command_block 0 replace {Command:summon Chicken ~ ~1 ~ {CustomName:Test}}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:gamerule commandBlockOutput false},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:"fill ~2 ~-2 ~ ~6 ~-2 ~ redstone_block"},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:"setblock ~2 ~-1 ~-1 command_block 0 replace {Command:/fill ~ ~ ~1 ~5 ~ ~1 stone 0 replace redstone_block}"},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:"setblock ~2 ~ ~1 command_block 0 replace {Command:/fill ~ ~ ~-1 ~5 ~ ~-1 redstone_block 0 replace stone}"},Time:1,Riding:{id:"FallingSand",Block:stone,Time:1}}}}}}}}}}}}}}}}