Marvel Legends Showdown (initially named Marvel Superhero Showdown) is a collectible tabletop game in which the primary component is action figures and cards.
Panel cards broke into two categories; Locations (Places in the Marvel Universe) and Plot Twist (Special events that occurred on that space) The goal was to move around the Panel card grid and knock out your opponents character with Punches, Kicks, or shooting them with an included projectile launchers.
The first two starters and booster sets were re-released with the new name, plus 2 new starters, 3 rider packs, and two new waves of boosters (Though these two waves 3 and 4 had limited release, seen in comic shops and KayBee Toys shelves rarely).
Toy Biz changed its name to Marvel Toys and then sold the rights to all Marvel action figure properties to Hasbro.
Marvel Legends Showdown was not one of the product lines that transferred over.