Out of the many words I understand clearly in their lyrics, the one that stumped me was 'catacrusis'. what the heck does -crusis mean?

Catacrusis
Closest I could get to a meaning. Probably just a little word play. Makes some sense with the lyrics.

I'm assuming you didn't see the video interview with Morean explaining the song titles and lyrics of Eidolon when it was first released.

It literally means something like ´stricken down´.
Kata = down Krouein = to strike

Which would fit in with the concept of the album because that third block of three songs is about the astral soul being reborn on the other side of the mirror and being removed from it´s position of allseeing / allknowingness and taken back to something similar to the life it lived before it came into contact with these forces that it foolishly thought it could understand or even use.

If you really want a clear explanation though, you should track down little clips the vocalist made about every song.