Emerald

Beat the Spire with the Silent. She's squishier than the Ironclad but has fantastic card draw and two strong archetypes: Poison (Noxious Fumes + Catalyst + Deadly Poison - just stack it and let it tick) or Shivs (Accuracy + Blade Dance/Cloak and Dagger). Poison is the beginner-friendly route and trivialises bosses. Whichever you build, you'll pick up Catalyst or Ninja on the way.