BO2 DLC 3: Buried (the first introduction of the ray gun mark 2)
BO3 DLC 3: Gorod Krovi (We got the ray gun mark 3 as part of the main wonder weapon of the map)
BO4 DLC 3: Alpha Omega (We got yet again the ray gun mark 2 and also 4 new variants)
BO6 DLC 3: Shattered Veil (For the third time we got the ray gun mark 2 again be introduced to the game and also including 3 variants, only one of them being completely new)