Phial of Xanthe's Blood

Open the treasury and search the upstairs office

Get the Treasury Key from the ledger in the cathedral’s ground-floor north-corner side room. A nighttime approach can use the roof and open tower to enter the cathedral. With the key collected, cross the courtyard to the square treasury building on its north side.

Inside the treasury, go upstairs to the side office and loot the golden reliquary. The blood phial is on this upper floor. The movable bookcase on the entrance level leads to the Stone Key cellar, a separate detour for The Hand of Fate.

Consume the phial from your inventory to obtain Blood Surge, then equip the ability for use in vampire form. Its base activation cost is 3 Activation Charges and 25% Health. It explodes its target and deals area damage; bosses take damage instead of exploding.

Blood Surge starts with a 3 m explosion radius. Later ranks increase that radius to 4 m, 5 m and 6 m, with Corruption requirements of 10, 12 and 14. The ability page lists the skill-point and time costs for each upgrade. The treasury pickup provides a route to Xanthe’s blood without relying on the choice to drink from her after a boss fight.