Evil in Waiting

Objectives

 * Collect all three vessels.
 * Perform the ritual with Valdar.
 * Defeat Hevnoraak.

Walkthrough
When the Dragonborn enters Valthume, a spirit named Valdar is encountered. The Dragonborn is instructed to collect three vessels in the cave and bring them back to Valdar.

The first vessel can be found in the Valthume area inside the room with the Draugr Deathlord that has two holes in the ceiling to the sky (requires activating a handle across an apparent dead end from an iron gate that causes a hidden door to open as well as the gate). It's possible that during the heat of the fight, the vessel might get knocked over so search the floor and in the bushes in the room. It looks much like an empty wine bottle, but will be labeled "opaque vessel"; the map arrow will show the location, but there will be no arrow shown in the room.

The second vessel is located in the catacombs in the locked room with a cage. When entering the first room there may be a chest and a giant spider with 1-3 smaller spiders with it. The cage with the vessel in it can be unlocked by pulling a chain after setting the correct combination on the rotating kiosks: dragon, hawk, wolf. It is the room with the three flamethrower pillars in it.

The third vessel can be obtained in the room behind the combination lock door. There is a Word Wall behind the third vessel that gives a word of the Aura Whisper shout.

Upon returning to Valdar, he will say that by pouring out the contents of the vessels, the lich entombed in the caves will be deprived from regaining its full power. After the Dragonborn pours the vessel contents into the sconce and sits in the throne, Valdar will reanimate Hevnoraak, who will still be formidable. (It should be noted that after sitting on the throne, the Dragonborn can immediately exit the throne and find a hiding spot before Hevnoraak appears. This can give sneaky characters a better chance to sneak attack him with a bow.)

Valdar then awakens the Dragon Priest Hevnoraak. Hevnoraak casts powerful lightning spells at the Dragonborn and summons Storm Atronachs. Beware of the lightning that Hevnoraak casts on the ground as it is debilitating to health and magicka.

When defeated, Hevnoraak will drop the dragon mask Hevnoraak which makes its wearer immune to both disease and poisons.

Trivia

 * If a follower is commanded to sit on the throne, Valdar will release Hevnoraak as normal allowing the Dragonborn to choose a better location to attack Hevnoraak from.

Bugs
Das Böse lauert
 * If the epilogue in the journal is read after completing the quest "Valdar" will be misspelled as "Vader".
 * The second vessel may be knocked behind the wall by Unrelenting Force, leaving the quest impossible to complete.
 * The puzzle door needing the dragon claw to open may some times freeze and become impossible if this happens on PC enter the console code "setstage dunValthumeQST 10" and return to where Hevnoraak lies (in Valthume). If you return to the door after defeating Hevnoraak it will function properly and you can retrieve the word of power. If this happens on the Xbox 360 you can save at the door and reload the game to fix the bug (does not always work, may need to revert to save prior to entering the ruins).
 * The spikes blocking the word wall may reactivate, this will leave you trapped.
 * If the quest is not marked as completed when Hevnoraak is defeated, talk to Valdar and the quest will update to completed.
 * You can either reactivate an earlier save or open the spikes by shooting arrows at the pedestal on wich the Opaque Vessel was.  Unrelenting Force shout towards that pedestal works too, but you need at least two words of the shout. If you are not trapped to open the spikes just jump on the activation block and back down.