Warding

Reforging an item at the Goblin Tinkerer costs one third of its current value (times the stack). A better prefix raises that value, so the next reforge costs more.

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

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

A reforge always gives a prefix.