I have added The Pact System (PDF 2.4 MB; ZIP 850 kb) to the downloads available from the site. This file includes the Gate Warden class for the Second World and an expansion for how one can cast spells and make deals with inhabitants of the outer planes.

The Pact System is a set of overlay mechancis that can fit in with the regular spellcasters, or via the Gate Warden class included. This allows the spellcaster to negotiate special contracts with extra-planar entities, who then can aid the caster in times of need.