Hawken, as well as a new co-op game mode.
The new mech is called the "Predator", and is based on the famed movie alien. The shape resembles that of the creature, and armed with a cloaking device. It even features a heat vision sight, but suffers from limited radar range. The mech also comes with The Breacher, a short-range spike gun, as well as a mine launcher.
The Invasion game mode is a horde-style mode in which up to four players deal with waves of enemy mechs, drones, and boss mechs.
Check out the Predator mech in the video below.