Drones are special items that appear when you create long matches, such as ones that explode vertically or horizontally. Drones can be moved on the board if they are not at the end of a line that you match. Take drones to where they will cause the most destruction or most use. Use them to reach elements that are hard to get to. Drones can be improved with the iridium you receive. Try to keep their improvements evened, as they will all be needed eventually.