Do you actually have to return the Spectral Essence to the Ancient Seer? Both bonuses (on the zest and the mission log itself) are marked as finished after you slay the Eidolon. Entropy 
(C) 12:54, 17 May 2009 (UTC)
- You will have to bring it back. The bonus is completed after you bricng back the spectral essence, although the bonus in the mission says "Kill the Eidolon"82.73.139.17 12:46, October 10, 2009 (UTC)