Counter

From The Five Pillars

For each attack you execute your victim gets counters. These counters allow the victim to strike back from whatever position, including outside your attack_range and even while you are in protection.

You can get both NP and land counters, land counters allow you to take as much land from the enemy as the enemy took from you and NP counters allow you to continue hitting till you did just as much damage as he did to you.

You will be able to keep hitting your attacker until you run out of either one of these counters.