Tyrant has the Epic Siege on Kor raid. The commander summons a Rat Catcher every turn, which can immobilize you and Phase you as well, blocking that unit from being affected by your own friendly activation skills. The core structure cards are some of the deadliest in the entire game, including the Cannon Wall, which has 15 health, and in 3 turns it Enfeebles all of your units, making them take 2 additional damage from all attacks and then proceeds to Strike all of them for 3 damage (after the effects of Enfeeble). There's also the Cluster Mine, which has Counter 10, which will pretty much kill any of your units that hit it. You think you can just Siege away those structures? Well, it also has two of its own version of the Gatling Tower, which will Strike one of your own units for 4 damage, inflict Chaos on all of your units, turning all of your own attack skills against yourself and thus blocking any Siege strategy you might employ, and Sieging all of your structures for 2 points of damage, all after only 2 turns. If that's not enough, the randomly generated player-available cards can make it even worse, including the Metalworks, the Usial, and Orwold's Reckoning, all of which can summon even more enemy units in addition to the commander's Rat Catchers. The best possible deck for this raid has only a 77% win rate, while all other raids have at least one deck with a 95%+ win rate, and it has 1.2 million health which requires great contribution from all 40 possible people to take it down within the 3-day time limit.