Abraxis is located in a semi-hidden alcove in the Scar. Meeting Abraxis is not required for the story, which makes this and the other related achievements missable if you do not visit him before defeating Pride. The closest fast travel point to him is called The Lowlands under Scar. From here, backtrack down the Stasis Hollow hole you climbed up before and roll back across the wall with the Force Hollow. After landing, you'll be able see a tornado you can boost up with Lightning Hollow. Follow the path and head up the elevator to meet Abraxis