Back to Between the Sessions
You can spend time between adventures learning a new language or training with a set of tools. You can also arrange for custom training scenarios with the DM if not covered here.
First, you must find an instructor willing to teach you. The DM determines how long finding an instructor takes and whether one or more ability checks are required.
Training lasts 250 days and costs 1gp per day. After you spend the requisite time and money, you learn the new language or gain proficiency with the new tool.