Xi

Xi is a Planet in the Faction Wars Update of SAS4. It is a Frozen planet, meaning that Zombies Living on Xi have slower Movement Speeds but higher defenses due to adapting to such cold climates. Xi is also the only source of Xi Tokens.

Faction Warfare Items
You can buy the following Faction Warfare items with Xi Tokens:

Havoc

Avalanche

Dynamo Helmet

Dynamo Chest

Dynamo Gloves

Dynamo Pants

Dynamo Boots

Trivia

 * The artwork of Xi Implies that it is possibly a Moon for Omicron.
 * Planet Xi is named after Greek letter Xi (Ξ/ξ/ξι).