For three years, City of Heroes let players don their best costumes and hit the streets in order to stop crime by using an array of powers. Its complimentary game, City of Villains, released in 2005, gave heroes some live competition, but didn't address one core issue: the general lack of upper-level content. Sure, Cryptic Studios made minor adjustments with past updates, including a high level PvP (Player vs. Player) zone. Quick-to-play police scanner missions and the incredibly challenging Statesman's Task Force brought Heroes in line with its villainous counterpart, while Issue 9's invention system got players to dust off their level 50 characters to fight for the sake of salvage collection. But it wasn't until some old foes made a sudden resurgence in Issue 10: Invasion that it became fun being fifty again.

An extra-dimensional alien race called the Rikti, (that brought humanity to the edge of extinction) found a way back to our world. Marked by a game-wide global event, where Rikti ships drop bombs across both Paragon City (Heroes) and the Rogue Isles (Villains) while they work to bring their crashed mothership to full power, they hope to pillage and destroy. Fortunately, Earth's forces prepared for this event. The Vanguard, a response group formed after first Rikti War, set up their base of operations in the Rikti War Zone (RWZ), formerly known as the Rikti Crash Site. From there, they recruit both heroes and villains to come together against this common threat.

Invasion hits with a bang, as Rikti bombers darken the skies and lob explosives. Players receive system-wide messages, warning them of which zone gets attacked next, providing them with the option to intervene or seek cover. They can attack the bomber ships, but their energy beams do tremendous damage, and the hulls are so tough that it requires a great deal of firepower to bring one down. So, players focus their efforts toward destroying unexploded bombs stuck in the streets before they go off. Destroying eighteen bombs earns players an accolade power to protect against psionic damage (the least resisted type in the game). The assault ends with Rikti soldiers teleporting in on players' locations. Players will naturally try to form large protective groups, causing an almost overwhelming number to come beaming into a chaotic fray. Those players who can't make the opening world event can look forward to random zone invasions in the future, as certain RWZ trigger a bombing attack.

Most of the action takes place in the RWZ itself, where both heroes and villains work cooperatively against the Rikti threat. War Zone missions earn a special salvage called Vanguard Merits, which gamers use towards crafting Vanguard armor, temporary powers and a Vanguard "Heavy" combat robot. The new Vanguard costume looks great, even without chest armor. Missions give players insight into the Rikti and the Vanguard, but those looking to earn a load of merits in a short period of time should perform a raid on the mother ship.