The boring achievement party passes by-the assassin's chamber refers to that library, and all you have to do is achieve the curse tower inside! On the map of the assassin's basement, a random intersection appeared, and my face was black. I almost reset the map more than 30 times before I painted it! I suggest you fully explore the map after you go in for the first time, and then TAB you will find the location of an intersection on the map, fix that location and randomly brush the curse tower, but the location of the intersection is random every time, and the curse tower also appears randomly. The trick is to reset every time you go in and find that there is no curse tower at that intersection.