Selected in September’s Patreon Poll as the next 5e race handbook to receive an update, I’ve given the Firbolg Handbook the usual post-Tasha’s updates.
Firbolgs are a little bit odd mechanically. They’re the only race I can think of with Strength and Wisdom increases, and their racial traits are both Wisdom-based (innate spellcasting) and Charisma-based (speech of beast and leaf). Finding a build which somehow threaded that needle was basically impossible, so the custom origin rules are a big help. Even then, few characters are have high scores in both Wisdom and Charisma, so often your best bet is to hope that no one cares about your Wisdom-based spellcasting DC (which is fine since none of the Firbolg’s saves require saving throws) and instead focus on Charisma-based skills so that you can talk to rats and such.