After the Vampire Clan escaped from the broken seal and took over the Kingdom of Edinburgh in just one night, Doni was among the country's Holy Knights turned into vampires and appointed as the messenger for the Vampire King to infiltrate the other kingdoms of Britannia and bring them into their fold, starting with Liones.
Arriving at the Liones Castle, Doni turned one unfortunate Liones Holy Knight into a vampire before heading to the throne room where King Bartra Liones resides and turned another one who was guarding the place into a vampire as well. Doni was this close in accomplishing his mission by taking out the king of Liones.
Suddenly, Zaratras appeared out nowhere and used Purge to revert back his two subordinates to human again, surprising Doni as he scaled on the wall to keep distance. Realizing that his human opponent's power is troublesome, Doni was confident enough that Zaratras won't able to keep up with his speed as he circled around the Great Holy Knight in quick movements but the Liones Great Holy Knight simply decapitated the Edinburgh Holy Knights of all four limbs in a blink of an eye with a single step and used his power again to turn him back to human once more.
Zaratras introduced himself to a tearful Doni who thanked him for freeing him from the vampiric curse before dying peacefully. Their battle alerted the Holy Knights of Liones who rushed to the scene.
After easily thwarted an attempted infiltration in Kingdom of Liones by a vampiric Holy Knight of Edinburgh Doni, Great Holy Knight Zaratras called for a meeting with Meliodas, Merlin, King, Dreyfus and Hendrickson about the impeding threat of the Vampire Clan that somehow escaped the seal after it was destroyed and how to deal with them.
In conclusion of the meeting, Zaratras ordered the deployment of the Seven Deadly Sins to retake the Edinburgh Castle and eliminate the Vampire Clan with Ban sent in for a recon mission while he, Dreyfus, and Hendrickson protect Liones from another anticipated vampire infiltration along with the rest of the Liones Holy Knights.