Predatory Edge is one of the two researchable abilities for the Crawler, the main early game Chaos unit. Its great ability and low cost make it a must-buy for large groups of Crawlers.
Upon researching the ability, Crawlers will receive a massive increase in speed. This makes them rival Order'sShadowrath in speed, and it makes them even faster than Bombers. It's a perfect ability to chase down and kill weaker units like Earths, Swordwrath, and Archidons, and frequently forces an Order player to fall back to protect their Archers, but it would be hard for crawlers to kill against a more tanky Armoured units or AoE, like a Charrog without heavy losses. . This is why the Crawlers' other upgrade, Pack Mentality, is a great asset and combination towards Crawlers. Usually players would research both abilities at the same time.