SkyOreGen (Skyblock Ore Generator)

Once you get a cobblestone block item you will be given a book. The book has a link to a trigger command to summon a villager called Greg. The villager has custom trades hovering over the item will give you the lore for the item (what it produces & chances). The first item is an item frame that should be placed within ~4 blocks of a cobblestone generator. The rest of the trades are the generator tiers, that you place in the aforementioned item frame. When a generator item has been placed it will search for valid cobblestone generators is range and give a chat message telling that is has found one. After that any time a piece of cobblestone is generated it will have a chance of converting the cobblestone into a different ore/block based on the generator item in the frame. When you enter the nether you will be given a second book to summon Ned. This villager has the trades for the basalt generator that convert basalt to nether related ores/blocks. Of course the books are there for easy summoning and killing of the villagers but they simply cause the player to enter a trigger command, so the commands can also be typed manually without the books.
Hope that helps.