Armeleon

I subscribed to this one in order to deny diamond gen, but I didn't see any hook for emeralds. Is there one in a newer release? Or is there an EventBus that denies biomes so I can override the Extreme Hills entirely?

I am writing a mod that needs to change what Emeralds drop. The easiest way I have found to do this is to remove the spawn, then write my own block which drops what I need it to drop. I have managed to extend the Extreme Hills biome class and add in the new Emerald for spawn, but it stills spawns the old Emerald in too. I don't want to have to edit the minecraft jar, but I can't think of anything else to try. Is there a forge hook I'm missing to cancel emerald spawn? Or maybe reduce its spawn frequency to 0? Any help would be more than welcome!