I know what it is.

It is the less common of the Spear of Destiny packs.
The original Spear of Destiny was one part of three actually. The remaining two expansion packs were not made by id, so id purists don't consider them valid.
There was other stuff included in the Super CD pack, but I am not sure what. I know it had a random level generator (like ROTT did) and the "hint books" for all three episodes.
The Super CD pack became what it did, rather than three separate commercial releases, because of the dramatic increase of 3D games (competition) that was on the way out. Some suggest it was because the additional episodes weren't very good compared to the original, but I have never substantiated this. Honestly, I have never played the other two episodes, but I do have them.
At one time, the Super CD pack would sell for $100+ complete and twice that if it were new/sealed. I never sold any of them, but I have seen them quite a few times over the years, and only recently (last 5 years) did the difference in price between Super-CD pack and the standard version disappear. I am not sure about this... but it seems like there are two version of the box, one which was just the yellow decal on the box, but later a second box was actually made.
Here is a short bit on MobyGames...
http://www.mobygames.com/game/spear-of-destiny-super-cd-packThat is all I can remember and some I can't remember. Hehehe
MrBlackCat