Leaderboard

Ok, so, 1, World implements IBlockAccess, you can check and cast. Or 2, IBlockAcess#getTileEntity().getWorld()

I can't really see an obvious way to tell how the entity was created. The spawn egg class (ItemMonsterPlacer) calls the code that creates the entity but doesn't seem to make any special call or post any particular event. I guess you could create a Capability for entities and replace the vanilla spawn eggs ((or maybe intercept the use of the spawn egg with an item use event) with your own version that not only creates the entity but also updates the Capability to indicate it was created by the spawn egg.