Orchid: Second riff in IMSWS (the main intro one)
Morningrise: The riff in BRI that goes electric, acoustic then electric again while playing variations on the same riff...about 2 minutes into the song.
MAYH: Intro to April Ethereal
Still Life: The opening of The Moor, the acoustic part that goes into the crazy metal riff.
BWP: The penultimate riff on the title track, you know, the part where he's singing " the sun sets forever"
Deliverance: The "chorus" riff on A Fair Judgement
Damnation: There aren't really "riffs" on here so much...
Ghost Reveries: TGC main riff