There are specific resources that will give you plenty of trouble when you are adventuring in Valheim. You might have trouble locating thistle in the Black Forest and Swamps, or you might be stuck trying to farm the numerous raspberries, blueberries, and mushrooms hidden through the Meadows and a Black Forest. Another difficult resource to find is guck, and you can only locate it in the Swamp. While it is in this region, how you acquire the resource is slightly elusive.
Guck is the glowing green goo growing on the sides of the large trees in the Swamp. You’ve probably noticed them and assumed they were aesthetic pieces to the environment. These are critical resources that you’ll probably want to grab right now and throw into a chest somewhere at your homestead to save for a rainy day.
You’ll need to bring an ax with you to chop it down. You cannot damage the tree that guck is attached to in the Swamp. Instead, you need to cut at the green portion of the tree and cut it down. When it breaks, guck will fall, and you can pick that up. Because most guck is attached to the upper portion of the tree, you may have to find creative ways to build a platform to reach these locations, or you can move on to find other sources of guck in larger swamps. You’re better off looking to find other trees, but guck is fairly difficult to find.
Thankfully, not too many items require guck in their recipes. However, anyone looking to create the Draugr Fang bow will need at least 10 guck to make it.