From the Chaosium website:
Items, Spells, and Creatures for Call of Cthulhu
This work provides a variety of creatures, technological items and spells for the Call of Cthulhu role playing game. The work follows the conventions presented in the rulebook in regards to creature statistics.
While most of the creatures presented are associated with the Mythos, many are not. The new Mythos creatures provide the Keeper with an opportunity to provide experienced players with some new surprises. The non-Mythos creatures enable the Keeper to provide the investigators with horrific foes that fall outside of the range of their knowledge about the Mythos, thus adding even more variety to the game.
A few technological items have been presented that are associated with some of the new creatures presented within these pages. Naturally, the items are not the sorts of things that one would find in the local mall.
Many new spells are included and all are relevant to the new creatures presented here. While many of the spells deal with summoning and binding, there are also spells for actually creating some of the new horrors. As usual, these spells will be employed mostly by the investigators’ foes.