Basic Trope: Early on in the game, a powerful character joins the party and nukes everything, before leaving.
Played Straight: Early on in Tales Of Troperia, the Five-Man Band of Bob, Alice, Emily, Charlie, and Dave are joined by the grizzled veteran Jason Bloodspiller, who is at level 27 while the heroes are at Level 1. He takes down everything in the game until he has to leave.
Exaggerated: He also has a sweeping attack, high stats, and a good helmet, armour, weapon, pair of gloves, and pair of boots equipped.
Justified: He has years of experience, but has to leave eventually.