|Because nothing says mechanic like a bright pink sweater.|
The hero is Unity, a maker of mechanical golems, who is either amazing or completely useless depending on how her cards come out, making her most effective paired with a deck controller like Visionary or Tachyon. About half of her deck is made up of 'Mechanical Golem' cards, which can only be played from her hand using her power or those on her other cards. Each of these little metal chaps is based on a card from another deck (there are versions of many of the original set heroes, Baron Blade's floating platforms, the raptors from Insula Primaris) and they each have a power that triggers automatically each round, meaning that if you get the right balance of golems and cards to activate them, Unity quickly becomes very powerful. On the other hand, the bots are relatively fragile, and it is also possible to end up with a hand full of unplayable golems or useless equipment.
The villain is Haka's nemesis, Ambuscade, a masked big game hunter who uses tech devices (and in particular a stealth field) to hunt superheroes. Fighting him is all about device control, and as a number of his gizmos explode if destroyed, scatter damage (for example, Tempest's innate power) is best avoided. He mostly uses projectile or energy damage, so heroes with a damage type nullifier can be very effective (Tempest once KOd is his worst nightmare.)
Finally, the environment is 19th century Silver Gulch, a mining town in the old west, packed full of cards representing a) time portals, b) bandits and c) cover for the bandits to use during gunfights.
It's well called a mini-expansion, but as part and parcel of my season pass is a welcome expansion to the game.