Shork Lefar's Spellbook contains the following spells:
Shork Lefar was a human Mage Apprentice & member of the likely defunct Half Star Cult, which centered around the use of the Half Star Portal Stones to open The Oakenveil Portal. He had some magics related to controlling Undead and at least for this campaign setting was murdered by the AAP before more was learned about him.
Near Oakenshire, very close to where the no longer existing town of Oakenveil was, Shork Lefar's Lair exists. It was created as a base of operations for a project to dig a passage to the buried location of The Oakenveil Portal. It consists of a hidden passage above ground where one must simply shove a rock and a chute into the earth acts as a slide to rapidly enter a room that (formerly) had Crawling Claws guarding it. That room in turn leads out to a hidden exit through a concealed door in a tree in one direction, and to a bunker full of books, oil lamps, and the formerly alive Shork Lefar.
Lair Epilogue - When the AAP went into combat with Shork they tore the place up. It is safe to assume that between burning oil lanterns on the walls and lots of combustible papers that the likelihood of anything relevant down in this lair, including additional spellbooks or notes involving portals or all things pertaining to them being destroyed, are high.