The Parry mod provides a chance to trigger a melee finisher when blocking while channeling. Simpler than the traditional counterattack maneuver which requires channeling at the proper timing of the attack, this mod can trigger automatically.
Certain melee weapons block more damage than others, increasing a Warframe's survivability while parrying.
If getting close to a ranged enemy, they will most likely melee hit you with their weapon to defend themselves, this maneuver can be parried and the player can perform a counter attack finisher on the enemy.
Finisher attacks triggered by Parry are affected by True damage.
When combined with Reflex Guard, triggering Parry no longer requires the user to block but does still require channeling.
Disarming enemies' ranged weapons (with effects like Loki's Radial Disarm) will force foes to switch to melee attacks that can be parried.
Certain special attacks can not be parried or trigger a counterattack finisher, though they will be blocked.
Grappling hook attacks (such as from the Grineer Scorpion or Infested Ancient Disruptor) will be blocked but not parried.
Normal knockback and knockdown rules for blocking still apply. Heavy enemy attacks like Seismic Shockwave or the Shield Lancer's charge will still trigger knockback but will not knock down a blocking player.
The counterattack maneuver can now be performed manually by channeling immediately before blocking an attack. Before this version, the Parry mod was the only way to stagger for a counterattack finisher.
The Parry mod will only work if one is channeling while blocking against melee attacks. When successful, a counterattack will be initiated, which momentarily stuns an enemy and allows them to be killed using a melee attack prompt similar to Stealth Attacks.