Small Aircraft
Flight Crew Multiengine
Flight Crew Last 90 Days 64; Flight Crew Total 853; Flight Crew Type 774
Communication Breakdown; Situational Awareness
ATC Issue All Types; Conflict NMAC
Flight Crew Took Evasive Action
Aircraft; Human Factors; Procedure
En-route to LNS I was cleared for practice RNAV31 @ LNS by approach. Contacted LNS tower. Heard ATC instruct Aircraft Y to change from 26 to right downwind for 31 and follow Aircraft X on approach.  ATC told Aircraft Y that Aircraft X was at it's 10 o'clock 2 miles.  Then told Aircraft Y traffic now at 12 o'clock at 1 mile.  ATC then contacted me (Aircraft X) that traffic was on right down wind for 31 at my 1 o'clock 1/2 mile.  I replied 'Looking for traffic'.  ATC instructed Aircraft Y to make a 30 degree turn to the left; I then saw something in my peripheral vision at approx. 3 to 4 o'clock. I looked and saw a plane at my altitude; about 1400 MSL; and I estimate about 200 feet away horizontally.  I immediately cut power and executed a left hand dive to avoid possible collision.  The aircraft had to have flown just over me and through the final approach path.  I must have squeezed the comm talk button on the yoke during the evasive maneuver and the ATC recording can hear me say 'Holy Sh*t' when I saw the aircraft.  Only after ATC asked Aircraft Y if he saw the traffic did its pilot confirm traffic.  I told ATC that when I get down I need to have a conversation with them and the pilot.  I was cleared to land and with very shaky hands;landed safely.  I was cleared by ATC to taxi to [parking] and then to call the tower when ready.
GA Pilot reported NMAC entering pattern while under ATC control requiring evasive maneuver.