Cloak of Titans by Jonathan Moeller
Spoilers for the earlier Cloak books ahead.
Many things come to a head in this volume. As in, it opens with Nadia observing that she started a civil war.
But she gets news of orcs massing for an attack from her goblin scouts, and they counterattack. Unfortunately, Duke Vashtyr and Baron Rymaris choose this to foment their conflict with the High Queen by Rymaris's defying orders. Also, they underestimate what Nadia will do in response.
Meanwhile, Victoria Carrow is looking for her moment to get back at the Duke for his deceit.
These things intertwine. It involves how much the Duke's mistress loves her son, a business in Alabama, the High Queen's Marshals, Shadowlands iron, and more.