I found this fun command on mcstacker and it didn't work right in in 1.8 because it had 1.9 features. So I went into the newest snapshot for 1.9
and pasted the command there. But instead of spawning little zombies it spawned pigs. Pigs with the name "Goblin" started spawning everywhere. As far as I can tell, everything else worked fine, like spawning delays. If it makes any difference, it was a setblock command, with a regular impulse command block set to UNconditional and always active. The seed is 1120123389898490186. XYZ cords are in pictures. Here is the command I was using and mcstacker:

http://mcstacker.bimbimma.com/#!27229

Thanks for reading
(gosh I feel like I forgot something...)