From the DelveRush Wiki · Equipment
Gadget upgrades
Mechanist Tamsin upgrades one physical gadget with disclosed cost and risk.
Upgrade preview
Tamsin shows the Coin cost, Core cost, success chance, and total break chance. A second confirmation starts the attempt.
Failure
A paid failure can leave the item unchanged or destroy only that gadget.
Salvage
Salvage returns 20 percent of successful base and tier Coin investment. It returns no Cores.
Failed attempts and addon costs add no salvage value.