Achitofel as military adviser: Berachot 3b-4a
King David's curse of Achitofel: Makkot 11a King David and Achitofel halting a potential earth-drowning flood, writing Gd's Name on parchment and sealing a hole: Makkot 11a
Achitofel wanted that which was not his, and so he even lost that which he had: Sotah 9b
