Complete every level on at least medium or harder. Once you return to the tavern, there should be a door above the northern (map view) staircase, with a big neon "OPEN" sign above it. Inside is a security camera, boombox (change your taverns BGM), a personal forge, and a single chest that only appears once. Inside the chest are heirloom weapons from every character's parents as well as 70k mana. Best of all, only the tavern only may enter this room.
ACHIEVEMENT - HOW TO UNLOCK Master Banker (10 points) - Store 15,000,000 Mana in your Mana Bank. Catch 'em All (10 points) - Store all Pet types in your Item Box or on your Heroes. Defender of Etheria (20 points) - Reach Hero Level 70. Dungeon Crawler (10 points) - Complete all levels on any difficulty setting. Dungeon Raider (20 points) - Complete all levels on Hard. Dungeon Defender (30 points) - Complete all levels on Insane. A Challenger Approaches (20 points) - Complete All Challenges on INSANE Difficulty. Survivalist (10 points) - Reach Survival Wave 15 on Medium Difficulty. Defense Is the Best Offense (20 points) - Reach Wave 10 on all levels in Pure Strategy on at least Medium Difficulty. Perfectionist (10 points) - Earn the Flawless Victory Award on all Missions on at least Medium Difficulty. Team Effort (10 points) - Complete all levels with 4 active players on at least Medium Difficulty. Legendary Defender (30 points) - Earn every Dungeon Defenders Accomplishment.