guaranteed punish; guaranteed counter-attack
Video game term for a counter-attack that is guaranteed to hit after blocking or evading an opponent's unsafe move.
If you block this move, you can get a guaranteed punish.
Learning guaranteed punishes will improve your win rate.
反撃 is a general counter-attack, while 確定反撃 specifically refers to a guaranteed punish in fighting games.
確定 means 'definite' or 'confirmed'; here it modifies 反撃 to indicate the counter-attack is unavoidable.
Compound of 確定 (definite, confirmed) and 反撃 (counter-attack). A modern video game term, likely coined within the fighting game community.