Guarding

The Goblin Tinkerer reforges an item for one third of its current value (times the stack). The current value already includes the prefix, so a better prefix makes the next reforge cost more.

With a Discount Card or a Greedy Ring equipped, reforging costs 20% less.

The Goblin Tinkerer’s happiness multiplies the cost by 0.75 to 1.5.

A reforge never gives no prefix.