9. XCOM 2: War Of The Chosen - Chosen Strongholds
War of the Chosen is an utterly fantastic expansion pack for the equally fantastic XCOM 2, and introduces three alien warlords who stalk your troops throughout the campaign, showing up every few missions to absolutely derail your plans to restore humanities grip on the planet.
You might think that giving them a spanking would be enough to deter them, but nope, in order to take them down permanently, you have to assault their stronghold and destroy the weird sarcophagus that keeps each alive. In fact, this strange device resurrects the Chosen, again and again, so you end up having to defeat another one, and another one, and another one... Jesus who designed this, DJ Khaled?
It’s a battle of endurance: your squad of squishy soldiers versus a fearsome alien warrior who keeps coming back from the grave. It seems inevitable that you’ll lose, especially when you can only hurt the device when it's resurrecting them. Yet this is the joy of XCom, it's brutally hard from start to finish and will make you pray so hard to the Gods Of RNG that you might as well start a cult.