Hey! its TVG33K is back with another only one command! this command allows you to spawn new mobs like Skeleton Horse, Zombie Horse, etc.  And not only mobs, but Primed TNT, Ender Crystals, and MORE the command below.

/summon FallingSand ~ ~2 ~ {Riding:{Riding:{Riding:{Riding:{Riding:{Riding:{Riding:{Riding:{Riding:{Riding:{Riding:{Riding:{Riding:{Riding:{Riding:{Riding:{Riding:{TileEntityData:{Command:"/fill ~2 ~-1 ~2 ~-2 ~4 ~14 minecraft:glass 0 hollow",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},TileEntityData:{Command:"/fill ~2 ~-2 ~2 ~-2 ~-2 ~14 minecraft:bedrock 0",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},TileEntityData:{Command:"/fill ~1 ~-2 ~3 ~-1 ~4 ~13 air",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},TileEntityData:{Command:"/fill ~1 ~-3 ~12 ~-1 ~0 ~12 redstone_block",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},TileEntityData:{Command:"summon FallingSand ~-1 ~3 ~11 {Riding:{Riding:{Riding:{TileEntityData:{Command:\"/gamerule commandBlockOutput false\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"/gamerule logAdminCommands false\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"give @p spawn_egg 1 91 {display:{Name:\\\"Spawn_Iron_Golem\\\"}}\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},id:\"FallingSand\",Block:\"iron_block\",Time:1}",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},TileEntityData:{Command:"summon FallingSand ~-1 ~2 ~13 {Riding:{Riding:{Riding:{TileEntityData:{Command:\"give @p spawn_egg 1 58 {display:{Name:\\\"Spawn_Ender_Crystal\\\"}}\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"give @p spawn_egg 1 54 {display:{Name:\\\"Spawn_Giant\\\"}}\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"give @p spawn_egg 1 58 {display:{Name:\\\"Spawn_Ender_Dragon\\\"}}\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},id:\"FallingSand\",Block:\"iron_block\",Time:1}",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},TileEntityData:{Command:"summon FallingSand ~0 ~1 ~11 {Riding:{Riding:{Riding:{TileEntityData:{Command:\"give @p spawn_egg 1 96 {display:{Name:\\\"Spawn_Primed_Tnt\\\"}}\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"give @p spawn_egg 1 51 {display:{Name:\\\"Spawn_Skeleton_Horse\\\"}}\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"give @p spawn_egg 1 54 {display:{Name:\\\"Spawn_Zombie_Horse\\\"}}\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},id:\"FallingSand\",Block:\"iron_block\",Time:1}",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},TileEntityData:{Command:"summon FallingSand ~0 ~0 ~13 {Riding:{Riding:{Riding:{TileEntityData:{Command:\"fill ~-2 ~4 ~1 ~2 ~4 ~-11 minecraft:bedrock 0\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"summon FallingSand ~0 ~1 ~-10 {id:\\\"FallingSand\\\",Block:\\\"redstone_block\\\",Time:1}\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"give @p spawn_egg 1 56 {display:{Name:\\\"Spawn_Killer_Bunny_Horde\\\"}}\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},id:\"FallingSand\",Block:\"iron_block\",Time:1}",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},TileEntityData:{Command:"/summon FallingSand ~-1 ~2 ~3 {Riding:{Riding:{Riding:{TileEntityData:{Command:\"/fill ~1 ~ ~ ~1 ~3 ~7 stone\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"execute @e[name=Spawn_Iron_Golem] ~ ~ ~ summon VillagerGolem ~ ~ ~\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"execute @e[name=Spawn_Ender_Crystal] ~ ~ ~ summon EnderCrystal ~ ~ ~\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"execute @e[name=Spawn_Giant] ~ ~ ~ summon Giant ~ ~ ~\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1}",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},TileEntityData:{Command:"/summon FallingSand ~1 ~1 ~3 {Riding:{Riding:{Riding:{TileEntityData:{Command:\"/fill ~-1 ~ ~ ~-1 ~3 ~7 redstone_block\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"kill @e[name=Spawn_Iron_Golem]\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"/kill @e[name=Spawn_Ender_Crystal]\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"kill @e[name=Spawn_Giant]\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1}",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},TileEntityData:{Command:"/summon FallingSand ~-1 ~0 ~4 {Riding:{Riding:{Riding:{TileEntityData:{Command:\"execute @e[name=Spawn_Ender_Dragon] ~ ~ ~ summon EnderDragon ~ ~ ~\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"execute @e[name=Spawn_Primed_Tnt] ~ ~ ~ summon PrimedTnt ~ ~ ~\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"execute @e[name=Spawn_Skeleton_Horse] ~ ~ ~ summon EntityHorse ~ ~ ~ {Type:4}\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"execute @e[name=Spawn_Zombie_Horse] ~ ~ ~ summon EntityHorse ~ ~ ~ {Type:3}\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1}",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},TileEntityData:{Command:"/summon FallingSand ~1 ~-1 ~4 {Riding:{Riding:{Riding:{TileEntityData:{Command:\"kill @e[name=Spawn_Ender_Dragon]\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"kill @e[type=Bat]\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"kill @e[name=Spawn_Skeleton_Horse]\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"kill @e[name=Spawn_Zombie_Horse]\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1}",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},TileEntityData:{Command:"/summon FallingSand ~-1 ~-2 ~5 {Riding:{TileEntityData:{Command:\"execute @e[name=Killer_Bunny_Horde] ~ ~ ~ summon Rabbit ~ ~ ~ {CustomName:\\\"The Killer Bunny\\\"}\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1},TileEntityData:{Command:\"\",id:\"Control\"},id:\"FallingSand\",Block:\"command_block\",Time:1}",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},TileEntityData:{Command:"/setblock ~ ~-10 ~1 wall_sign 2 0 {Text1:\"===============\",Text2:\"{text:\\\"Click\\\",color:\\\"dark_red\\\",clickEvent:{action:run_command,value:\\\"/fill ~2 ~2 ~ ~-2 ~-4 ~13 air\\\"},extra:[{text:\\\" to remove\\\",color:\\\"black\\\"}]}\",Text3:\"this structure\",Text4:\"===============\"}",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},TileEntityData:{Command:"/setblock ~ ~-12 ~1 wall_sign 2 0 {Text2:\"{\\\"bold\\\":true,\\\"color\\\":\\\"dark_blue\\\",\\\"text\\\":\\\"Vanilla\\\"}\",Text3:\"{\\\"bold\\\":true,\\\"color\\\":\\\"dark_blue\\\",\\\"text\\\":\\\"Mod By:\\\"}\",Text1:\"{\\\"bold\\\":true,\\\"color\\\":\\\"dark_blue\\\",\\\"text\\\":\\\"More Spawn Eggs\\\"}\",Text4:\"{\\\"bold\\\":true,\\\"color\\\":\\\"red\\\",\\\"text\\\":\\\"TVG33K\\\"}\",y:4,x:656,z:263,id:\"Sign\"}",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},TileEntityData:{Command:"/fill ~ ~-15 ~ ~-1 ~2 ~ air",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},TileEntityData:{Command:"/fill ~-1 ~-16 ~ ~-1 ~-1 ~ redstone_block",id:"Control"},id:"FallingSand",Block:"command_block",Time:1},id:"FallingSand",Block:"redstone_block",Time:1}