All four will report to Auburn in January and begin classes.
Williams is a 6-foot-3, 215-pound receiver that accumulated 2,028 yards and 26 touchdowns during his two seasons in junior college. Williams ranks as the nation's No. 1 junior college player nationally.
Auburn signed Williams after a fierce battle with LSU - the program Williams was committed to before switching to Auburn in July. Auburn assistants Dameyune Craig and Rhett Lashlee recruited Williams to the Plains.
"We're going to throw it more next season," head coach Gus Malzahn acknowledged during his Wednesday press conference. "You just get him (Williams) the ball and he makes things happen."
Moncrief, a 6-foot-3, 220-pound safety originally from Prattville (Ala.), is ranked the nation's No. 1 junior college safety and No. 16 overall junior college prospect. Moncrief is projected to begin his career at the "star" position.
Dampeer is a 6-foot-3, 300-pound lineman who committed to Auburn during an official visit this fall. Dampeer is the nation's No. 1 center and No. 91 overall junior college prospect. Dampeer was recruited to Auburn by offensive line coach J.B. Grimes.
"I'm excited about coming to Auburn. I'm part of a family, everybody I come in contact with is family. I'm become a part of the best program in the nation and I thank God for this opportunity," Dampeer told AuburnSports.com.
Lambert committed to Tennessee over Auburn and others earlier this year, but Auburn's late push paid off. Malzahn and defensive line coach Rodney Garner made an in-home visit with Lambert recently, who will play defensive end at Auburn.