Golden Finger金手指
jīnshǒuzhǐ
Fan slang for the protagonist's unfair advantage: the grandpa in a ring, the system, the mysterious pagoda, whatever guarantees they outpace the world.
The term comes from video game cheat devices and is used with full self-awareness: readers expect a golden finger the way mystery readers expect a corpse. Classic forms include an old master's soul sealed in a ring (Battle Through the Heavens), a game-like "system" that issues quests and rewards, a library of every technique, or memories from a previous life (Tales of Demons and Gods).
Structurally the golden finger is what lets an underdog protagonist plausibly compete with clans that hoard resources across millennia. Whether a story feels fresh often depends less on having one than on how honestly it prices the advantage: the best novels make the cheat create problems as fast as it solves them.