If you’re familiar with the central double decrease (cdd), then the central quadruple decrease (cqd) will be easy to conquer. This decrease kicks the cdd up a notch by decreasing 4 stitches rather than just 2 stitches. A little trick ensures the central stitch stays on top!
If you’re working Peacock Ridge, you’ll come across the cqd on the wrong side. Here’s a video showing how: