Once Tarnished have crossed the Bridge of Sacrifice and entered the Weeping Peninsula in message in Elden Ring to her father in Castle Morne.
Castle Morne is located at the southernmost tip of the Weeping Peninsula. Tarnished can reach the stronghold if they continue following the path southward. However, making the journey during the day is recommended, as a high-level Night's Cavalry will spawn on the road after nightfall. Furthermore, a Golem archer will begin firing at the player when they approach the castle. To avoid its arrows, hide behind the giant chunks of rubble near the roadside. The moment the Golem begins to nock another arrow, rush to the next piece of debris. Once Tarnished get close enough, they can take down the giant fiend by striking its weak points around its ankles.
The next step is to find Irina's father, Edgar, at the top of Castle Morne's northeastern tower. The fort is full of hostile mobs, and although most of them are relatively low-level, their large numbers can quickly overwhelm the solo protagonist. Hence, Tarnished are advised to progress cautiously by clearing every area and not rush in without discretion.
How To Complete Irina's Quest In Elden Ring
To reach Edgar's tower, go behind the site with the massive mound of corpses to find a ladder leading up to the walls. Go past the fighting mobs in the southeast to encounter Edgar. After giving him Irina's letter, he will state that he cannot leave until the "treasured sword of Morne" has been recovered. To progress the story, confront Leonine Misbegotten, Castle Morne's boss, on the small island south of the Dungeon. After retrieving the Grafted Blade Greatsword in Elden Ring, return to Edgar to tell him the good news.
Next, Tarnished must travel back to Irina's location to find Edgar grieving over her dead body. This event, however, does not mark the end of Irina's questline. The player must journey to Liurnia of the Lakes and head to the Revenger's Shack, located on the far western side of the region. After entering the shack, the anguished and vengeful Edgar at Revenger will invade the protagonist's world. Once slain, he will drop a Shabriri Grape, an essential quest item required for Hyetta the Finger Maiden.
Elden Ring is available on PlayStation 4, PlayStation 5, Xbox One, Xbox Series X|S, and PC.