Ok so the system works like this. 1. You have a perk called "Energy Drain" the text description for this perk is " A Powerful melee attack that drains energy from enemies and uses it to reduce the cooldown of your grenade". The Energy Drain effect is in that description. Additional perks in the same column do not change this effect but merely have another effect triggered by the same action that triggers Energy Drain. 2. You are using the perk "Embrace the Void". The text description for this is "Damaging enemies with Nova Bomb or any grenade triggers the Energy Drain effect. What the combination of these two means is that Grenades and Nova Bomb will trigger the Energy Drain Effect. This is not extended to the Surge, Life Steal, or Soul Rip effects as they are triggered only by a melee attack in parallel with Energy Drain but not as a supplement to it. This is intended functionality. Hope that helps explain this.