Blessed as far as the oldskool goes. Can't beat "Brainstorm" and "Desolate Ways" is nothing less than complete genius. Richard Brunelle doesn't get enough credit for that one.
Formulas for actually being their best album IMO, in terms of sound and construction, and the asbtraction of it all. Invoction and Hymn to a Gas Giant are brilliant enough, never mind Chambers of Dis or fucking HEAVING EARTH. They've never topped it.
Heretic because it sounds so wierd and has a few vicious riffs throughout the tracks (Enshrined, Stricken Arise etc), also some great instrumentals (Abyssous!!!), shame about the complete lack of bass though (apart from about 3 seconds in "Place of Many Deaths" i think it isn't there at all).