Primarily used in gaming contexts, especially RPGs, to describe a powerful or decisive blow. Can also be used figuratively for a well-timed, impactful action.
Using this skill makes critical hits more likely.
His remark was truly a critical hit.
A direct loanword from English, used in gaming contexts. 会心の一撃 is the native Japanese equivalent and carries a slightly more dramatic or literary nuance.
Compound of 会心 (satisfaction, gratification) + の (possessive particle) + 一撃 (one blow, single strike). The term likely originated in gaming to translate 'critical hit' and has since gained figurative use.