In a blog post on the Treyarch website, they explain that January 15 marks 115 Day and is a nod to the element 115, which plays a part in Call of Duty Zombies lore. Until January 18 you can earn double XP, double weapon XP, and double Nebulium Plasma across all platforms.
Three new epic craft-able elixirs are being added this week. Perk Up will grant 4 new random perks, Refresh Mint resets cooldowns for your team, and Conflagration Liquidation gives you a bonfire sale power-up. There have also been some balancing changes to existing elixirs.
Gauntlets, a new mode featuring 30 rounds of ever-changing challenges are being added for PS4 players. Each round will see different restrictions or modifiers put on you and your team. If you do manage to complete rounds 10, 20, and 30 you can earn rewards including a special emblem adornment for finishing all 30 without any strikes.