MobArena
The structure is a mob arena. The mobs can appears when a player or mob walk on a pressure plate.
I had test in severals versions of minecraft and I see that the mobs can spawn without problems (except spiders sometimes) in the versions :
1.5 ; 1.6 ; 1.7 ; 1.8 ; 1.11 ; 1.12
The others versions cause problems becauses the mobs spawn under the arena or not attack the player. Version with problems : inferior to 1.4 ; 1.4 ; 1.9 ; 1.10
Don't hesitate to modify the structure if you want to adapt it to your needs.
