Before facing the Act 3 boss, ensure your deck is as strong as it can be. Use shops for final card removals or key relics. Upgrade any remaining crucial cards. If you're attempting to reach the Heart, you'll need to collect three specific keys throughout your run: one from an Elite, one from a Campfire, and one from a Chest. The Heart fight is an extreme test of your deck's resilience, requiring immense damage, block, and status management.
