Originally Posted by Womi
Do you need to complete all challenges on 4 star difficulty too?
Yes you do sadly.
10K achieved 1/21/2007 achievement that put it over 10K Champion of Cyrodiil from Oblivion
100K achieved on 12/5/2012 achievements that put it over Late for the Prom from Call of Duty: Black Ops II
Most proud achievement Veteran Gear from Gears of War 2