Hey just in case you missed it I managed to get another post off in primal force yesterday. Sites been pretty active though which has shunted it back a page or two.
Alceaus wants to have the nighsisters teach Rareth to summon and control Spirit Ichor. Which of course involves shaman blood rites and tripping like mad on shrooms.
It can do a number of awesome things. I was thinking Rareth would probably draw his out through something physical like violence or murder though it's really up to you.