Amethyst

Beat the Spire with the Watcher, the monk added after launch. She fights by switching Stances - Wrath (deal double, take double) and Calm (bonus energy when you leave it). She's the most powerful and most fragile class at once: a Wrath burst deck can delete bosses, but a careless turn in Wrath can delete you. Learn the Eruption/Vigilance stance dance and she melts the game. A Divinity + Mental Fortress deck, or a Pressure Points setup, are both strong and beginner-viable.