db={"projects":[{"name":"Project 1","skillsetCombinations":[["A","B","D"],["A","B","E"],["A","C","D"]]},{"name":"Project 2","skillsetCombinations":[["X","Y","Z"],["A","B","D","E"],["U","V","W"]]},{"name":"Project 3","skillsetCombinations":[["A","B","E"],["A","C","D"],["A","B"]]},{"name":"Project 4","skillsetCombinations":[["X","Y"]]},{"name":"Project 5","skillsetCombinations":[["A","B"]]}]}

db.projects.aggregate([{$unwind:"$skillsetCombinations"},{$match:{"skillsetCombinations":{$nin:[/**"A"*"B"*/"C",/**"D",*/"E","X","Y","Z","U","V","W"]}}}])