Queen Eva is a Spirit affinity legendary from the Dark Elves faction. Queen Eva is one of the best campaign farmers in the game and is a great dungeon champion up until level 15. After that her abilities do not scale high enough and she becomes a squishy glass cannon. If you can keep her alive she can offer some Ice Golem support with her ability to block revive.
Queen Eva is so good as a campaign farmer due to her inbuilt crit bonuses. She has an all battles 19% crit aura and her A3 gains an additional 15% chance to crit meaning you can build her with just 66% crit rate and more damage.
Overall I feel like Queen Eva is badly in need of a buff to allow her to be relevant through to end game.