Christmas titles & tags are gained as a result of completing levels 15 and 20 respectively.
Further information can be found here:
Aren’t entirely happy with the item you got by completing the Zombies Christmas Event? Offer to trade with another person for their title or tag here!
Please cooperate with respect.
Merry Christmas to all! 
Offering to trade my tag for ‘the Nutcracker’ tag, if anyone who has it is willing/wants this one. Additionally, I can also offer one R10 color alongside, or as a standalone trade item from the screenshot below (Top = 220, 20, 40. Bottom = 220, 0, 0).
Trading for the “Slayer of Frost Moon” Tag
Event rewards are really buggy, sometimes not granting certain rewards that were stated.
Its also possible to not receive vanity from the lootbox, not receive a title/tag from the lootbox or receive both a title AND tag from the lootbox along with vanity.
