Heroic Lunge in an Ability in Death's Gambit. Abilities are special skills that can be performed depending on the Weapons you have equipped (much like Dark Souls 3). Ability use consumes Soul Energy, that you get from performing specific actions based on your Class.
Heroic Lunge Effect
Jump into the air and land with a powerful strike. Increases longsword damage by 25% for 8 seconds. If this kills an enemy, cooldown is reset.
How to unlock Heroic Lunge