The mini-expansion introduces a climax to The Codex of the Infinite Planes Saga, where players must face the sinister presence of Vecna and his cult in Morgrave University. Vecna Unleashed offers new adventures in various locations, including Sharn, the Plane of Water, the Abyss, and the Astral Plane. Players will battle against new monsters such as humanoid rodent Wererats and abyssal demonic Vrocks, while also unlocking a new Epic Destiny called the Machrotechnic.

High amongst the Sharn city of Towers, something sinister is afoot in the halls of Morgrave University. The Codex of the Infinite Planes has escaped to the academy, and with it comes the dark presence of Vecna and his cult. Now with the university's vast collection of rare and powerful artifacts under their control, the destiny of not just Sharn but the entire Eberron plane hangs in the balance.