The Blacksmith's Apprentice

The Blacksmith's Apprentice is a character that appears in all Passages between biomes, but only after defeating a boss for the first time and meeting him and The Blacksmith in the subsequent area. He upgrades and re-rolls the affixes of Gear, at the cost of some Gold.

Minor Forge
The workstation of the Blacksmith's Apprentice. The player can interact with him to access the Minor Forge.

Upgrading Gear
The player can spend gold to upgrade their preferred gear to the next quality level. The amount of gold is a proportion of the gear's price in the Shop, rounded down to the tens:

Gear can only be upgraded once, unless the player has bought the Advanced Forge upgrade from The Collector.

It should also be noted that Amulets are not able to be reforged or upgraded in any way.

Rerolling Modifiers
Rerolling (referred as "Reforging" in-game) lets the chosen gear have new Modifiers. The new Modifiers are chosen randomly and will replace old ones. The player can reroll as many times as they want, as long as they can afford it. In case of legendary quality items, the star affix on them gets swapped with another of its kind while still having the possibility to get a second one.

The equation for the cost of rerolling modifiers is (Gear price) &times; (Reroll multiplier)
 * The cost is rounded down to the tens.
 * Gear price is its base price + (100 &times; (Gear level - 1)). This gear's price is different from the prices in shops.
 * Reroll multiplier is a number that increases with each reroll. It scales differently with each quality. These are the approximate values of the first 30 reroll multipliers for each gear quality:

First encounter

 * "Hey, you there!"
 * "I work for the Blacksmith!"
 * "I can patch up your gear for cheap..."
 * "I'm not really supposed to be here..."
 * "Let's just keep that between us, ok?"
 * "Right, c'mon then, how much have you got on you?"