Energy Pulse is an ability that Hayden acquires during Chapter 5 after taking out enemy troops using the Jackal. It allows him to create a burst of elemental energy around him to take out groups of enemies by clicking the right analog stick on consoles or by pressing the T button on PC.
It can only be used when the Glaive is charged using one of the three elemental powers - fire, electricity, or ice. Once it is charged, pressing the correct button will cause Hayden to raise his glaive and send out a shockwave of the corresponding element. It is very useful for taking out a group of enemies that are swarming Hayden.
Using it will cause the element charged in the glaive to dissipate, requiring another charging up to use Energy Burst again. After using it, there is a short cooldown period where Energy Burst cannot be used again, regardless of whether the glaive is charged with an element or not.