Amongst all of Vaermina's pets, this spirit remains the most hidden, the most secretive. He is known by many names, but none of them true, which has made his summoning impossible for centuries.
But Vaermina whispered his secret name in my sleeping ear last night whilst I dreamt of darkness. She bid me to unleash his foul influence in Tamriel and to drive the people of that world to distrust and betrayal.
To summon the Omen of Deception, you must first light the four braziers, slay whomever you offer as sacrifice, and finally speak the Daedra's true name.
The sacrificial blood must be freshly spilled, but take great care to ensure the sacrifice is fully dead. If the sacrifice were to retain any trace of life, the Daedra would be summoned in a weak and susceptible state. And were something to happen to her pet, Vaermina would not be pleased.
The Daedra's true name is Ykal. Speak it and he will come—but make sure his vessel is prepared.