New blocks that serves special effects in an specific area?
Similar to the Auto-smelt custom enchantment Pickaxe,
Instead of tools, maybe we can have some blocks that are required to be custom crafted. For example a goldblock surrounded by 4 seeds and 2 melon seeds and 2 pumpkin seeds. Then you have to place it along with some other blocks to form a specific figure. Therefore, creating a special effect around the area, maybe increase your crops growing speed 3x faster? Increase dropping from crops when harvest?
Maybe a useful custom crafted creeper repel block that requires emeralds and diamond to craft?