Note that Valpurus is a busy god and does not respond well to ordinary mortals bothering Him with their prayers. You should only pray to Valpurus after becoming His champion. Offer sacrifices to Him until He declares you His champion, then it is safe to pray. Repeat this process after each prayer, as Valpurus is also a fickle god and his favour does not last.
When pleased, Valpurus will recognize you as his champion and grant you a sword and a shield of valpurium:
- valpurium two-handed sword [1500g, DAM 7-12, accurate, almost unbreakable],
- valpurium shield [1050g, highly accurate, almost unbreakable].
You hear a booming voice: "I RECOGNIZETH THEE AS MINE OWN CHAMPION! JOURNEY FORTH WITH THESE ARMAMENTS TO DEFEAT MORTIFER AND ALL THE CHAOS HE HADST SOWN!" A set of holy arms appear from nothing.
Subsequent prayers will get you a Holy Handgrenade of Antioch each.
As all gods, Valpurus may also grant you a temporary pet angel. Note that no matter how high is your favour with Valpurus, he will not summon his archangel Inlux, since she is in the service of the Cathedral. Valpurus will also not regrow your lost limbs.
When angry, Valpurus smites you with a small hammer, doing direct damage to your head.
As all gods, Valpurus can also summon a hostile angel when extremely angry.
Other altars of Valpurus can be found randomly in the dungeons.
If you can raise you piety with Valpurus high enough to become his chamion, the sword and shield he offers are end-game tier gear that can be obtained relatively early in the game.
Note however that you cannot become a champion of both Valpurus and Mortifer, so if you plan on acquiring Neerc Se-ulb, you should refrain from praying to Valpurus.