Is it possible to get "Soul Eater" randomly?

EDIT : I had an Omen on me that granted the buff. Didn't see the message and forgot to put it in my chest! My bad..

That might be a dumb question, but I'm leveling a slayer and I randomly got the "Soul Eater" buff in the chamber of innocence (Act 5) for no reason... I have no clue how?

I have basic leveling uniques (Tabula, wunderlust, goldrim, etc.) nothing that could give me the buff... also nothing that could steal buffs (no HH or inspired learning).

Is this a bug or I just don't understand something?