Recovery tools: Recursion, backup engines, or redundancy
I feel like the Assassin's Creed designers had Etrata in mind when designing the set because there's so many cards here that work with her specifically and no other legendary in the set: Roshan, Hidden Magister is the most notable example here, turning ALL of our face-down creatures into Assassins, giving them menace, and adding card draw to when we flip them up
Drawing cards has a less immediate impact than dealing damage, but an extra card a turn generates plenty of staying power to win a long game
It can also utilize its large HP pool to use moves like Rest, which fully heals it and puts it to sleep, combined with the move Sleep Talk, allowing it to attack even while asleep
Im confident that there has to be a way to break this card somehow, but it currently escapes me