noun
killer technique; surefire assassination method
General term for a lethal or decisive technique, often used in fiction, games, or metaphorical contexts.
彼は必殺技を繰り出して相手を倒した。
He unleashed his killer technique and defeated his opponent.
noun
special move; finishing move
In martial arts, a unique or signature lethal move associated with a particular fighter or style.
この流派には代々伝わる必殺技がある。
This school has a special move passed down through generations.
決め技 is a finishing move in sports or entertainment, not necessarily lethal; 必殺技 implies a killing or decisive blow.
Compound of 必殺 (certain kill) + 技 (technique). The term is widely used in manga, anime, and games to describe a character's ultimate attack.