Evil in Waiting

Walkthrough
Through the first entrance of Valthume, there will be a ghost named Valdar who gives this quest.

Collect the Vessels
Once this quest is completed the Dragonborn will have gathered three Opaque Vessels filled with a substance...

Perform the ritual with Valdar
... which must then be poured into a sconce (shown in quest). Then proceed to sit in Hevnoraak's throne. The dragon priest, Hevnoraak, will then rise out of its coffin demonstrating his ire.

Defeat Hevnoraak
Once defeated, there is a passage near the coffin which leads to a word wall containing the word Yah (Seek) which is part of the shout Aura Whisper.

Das Böse lauert