Does anyone know where to get a copy of Castle Defenders for 1.7.10? I had it ages ago and it looks like the minecraft forum link for it is dead. I don't know if there's a modpack out there that used it for that version of MC.
Basically you could craft these blocks that when you placed them, would spawn a specific type of unit up to a certain limit. Those units would usually patrol the area around the block, and attack mobs.