Snakes 'n' Ladders
Make a mistake or drop a stitch in this pattern and there is not much hope in saving it. When a heroic rescue is attempted the situation just goes from bad to worse! You're dealing with twisted knit stitches that occasionally change to purls (that aren't twisted) as they go under a cable and change direction. If a stitch is on the run it can get very confusing faster than you can curse.
Note the lack of a needle in this picture? That's because it is about to be ripped back all the way to that plain toe section. NEXT time I'm putting in a life line. I would just scrap the whole project if I didn't want this particular pair of socks so bad.
How fitting that Yarn Harlot's entry for today on the "Never Not Knitting", Page a Day calendar is about lifelines. Quote: "you'll probably never need it if you do it, and regret it very deeply if you don't".