Requested by @ProfessorProspector for https://github.com/TechReborn/TechReborn

well probably more for an addon but yes.

Preferably I could just extend a BaseCage and tell it when to handle the mob spawning. Something like canSpawn() and I could return true if it has enough energy and stuff.

Well I assume you would want to be able to modify speed as well

ah yes, that too. I also need to add a Nicolas Soul Cage that is super fast :P

I'm not sure how feasible doing it all through the API is. But I can move some checks into their own methods. So you'd extend TileEntityCage and override getCooldown() (to change spawn speed), getSpawnAmount() (to change amount of mobs spawned), and canSpawn() (if spawning is allowed). Other than those three methods (and any helper methods you need for your own stuff), the rest should be able to be left untouched.

http://paste.ubuntu.com/15623779/

Yeah, looks good.