It was the first operation case to be severely restricted in volume with each player only being eligible to obtain up to a maximum of 9 cases. As a result this heavily limited the total number of Hydra cases that were awarded to operation pass holders, which in turn has driven up the price of the case higher than any other operation case (with the exception of the Bravo case).
At the conclusion of Operation Hydra the case was immediately moved to the rare drop pool.
The Operation Hydra Case has a chance of being offered to players with prime status once per week as part of their weekly care package. The odds of receiving a case from the rare case drop pool is 1/100 or 1%.
Alternatively, it can be obtained by trading with other players, or purchasing from the Steam Community Marketplace and some third-party marketplaces.