Tuba Merchant

Backstory
Tuba Merchant is the benevolent twin of Tuba Wizard. Unlike his brother, he cares little about the ongoing war. Tuba Merchant dedicates his life to running a shop for anyone with enough coin to buy items.

Though passive in nature, he will attack anyone to preserve the integrity of his shop. Attempting to steal from him will initiate a boss fight. The difficulty of the boss fight is determined on how expensive and/or powerful the item you tried to steal.

Easter egg
Going to the left of the shop with the red key from the Deep Forgoten Cave will open a secret door. You have to beat the Tuba Wizard first and later on you can fight the secret boss: Tuba Merchant - who desire to revenge his brother's death.

Trivia

 * Tuba Merchant and Tuba Wizard are identical twins, and share the same base assets.
 * Stealing from the Tuba Merchant unlocks the achievement "Thief"