Pandora

Pandora is the conjectural name of a mysterious cubical object that fell from space and crash-landed on Earth. It is a major plot point in the story of Street Fighter X Tekken.

Story
The story reveals that this unknown object has crash-landed somewhere in Antarctica. With its origin and purpose unknown, the object has gained major media attention. Studies on the object have revealed, however, that it appears to draw power from conflict, during which it releases a powerful energy. Researchers fittingly name it Pandora, after the Greek mythological figure and the conflict she unwittingly created by opening a box given to her by the gods.

The object has also drawn the attention of many Street Fighter and Tekken characters, whose motivations are explained below.

Street Fighter

 * Ryu searches for Pandora in the belief that it has some connection to the Satsui no Hado. Ken joins him, acting out of concern for his friend.
 * Guile is sent by his superiors to investigate Pandora. Abel learns that Shadaloo is also seeking it, so he teams up with Guile in the hope that he'll learn more about who he is.
 * After discovering that both Shadaloo and the Mishima Zaibatsu are heading to Antarctica, Chun-Li follows to investigate their movements, inviting Cammy to accompany her.
 * Dhalsim heads to Antarctica after several children in his village disappear. Sagat joins him, hoping to find a young girl from his village who also went missing.
 * Poison and Hugo learn that the media have gathered in Antarctica, so they decide to travel there to "show off their assets".
 * Learning about Pandora from a subordinate, Rolento plans to destroy it in order to prove how strong his army is. He seeks assistance from the elders of Ibuki's village, who force her to assist him.
 * Zangief seeks Pandora to prove his loyalty to Russia. He asks Rufus to assist him in his journey; Rufus wants to get rid of Pandora after its media attention overshadowed that of his victory at the North American Martial Arts tournament.
 * Under orders by M. Bison from Shadaloo, Vega and Balrog head to Antartica to obtain Pandora, despite their mutual dislike for each other.

Tekken

 * Kazuya plans to acquire the power of Pandora in order to strengthen his inner devil power and wrest control of the Mishima Zaibatsu from Jin. He is joined unexpectedly by Nina, who had previously tried to kill him, but now seems to want to assist him.
 * King learns that a man resembling Armor King, long-since killed by Craig Marduk, has boarded a ship to Antarctica. After Marduk also learns about this, the two team up and begin an uncertain trip to the South Pole.
 * Julia learns about Pandora's power and, worried that it could easily be used for evil, hires Bob to assist her in finding it.
 * In their search for Pandora, Shadaloo and the Mishima Zaibatsu come into conflict and end up destroying the grounds for a mixed martial arts tournament. Hwaorang and Steve, who were fighting each other at the time, form a temporary alliance to exact revenge on the two companies for interrupting their battle.
 * Yoshimitsu discovers that his sword is resonating, and believes it has something to do with the mass of fighters heading to Antarctica. He encounters Raven, who is also investigating the issue. Although he does not trust Yoshimitsu, he agrees to work with him under the condition that he takes lead.
 * Heihachi learns that both Kazuya and Jin are heading to Antarctica to seek Pandora. He decides to head out there himself in order to kill them, take the box's power and claim power of the Mishima Zaibatsu for himself. The revenge-fueled Kuma assists his master in his journey.
 * Lili decides to retrieve Pandora for the sake of her father, but unable to do so alone, she is forced to ask her rival, Asuka, for help.
 * Marshall Law has a mountain of debt, but after learning of Pandora from the news program and smelling the scent of money, he decides to travel to the South Pole with Paul Phoenix.

Gameplay
During gameplay, Pandora can be triggered if the character you are currently controlling has less than a quarter of their health remaining. When used, it provides a monumental power boost, and an infinite Cross Gauge. However, there are two notable drawbacks.
 * 1) Pandora requires the sacrifice of your current character. Depending on the situation, this may not necessarily be a drawback; one can trade in a partner on their last slivers of health for a more powerful character.
 * 2) A timer meter starts above the user's life meter. Upon triggering Pandora, the user will have a limited time to win the match afterward. If the user fails to end the match before the meter runs out, the character is knocked out, thus causing them to forfeit the round.