Vault of the Faceless Giants

From publisher blurb: This module includes several encounters that use mechanics and content from Old School Adventures Accessory PX1: Basic Psionics Handbook. Additionally, many of the encounters will be made more enjoyable by having a character of the mystic class in the party. If you do not plan to use the material from the Basic Psionics Handbook, some of the encounters may require modifications in order to facilitate playability.