Dead Man's Party
Trying to find out when the Day of the Dead (Nov. 2nd) actually was, I found the holiday interesting. Unlike Halloween, which has turned into a commercial candy and costume venture, Day of the Dead is much more joyful, yet realistic.
The holiday is the one day when it's easiest to communicate with the dead. The holiday is not supposed to be mournful. People celebrate this day by bringing flowers, food, gifts to cemeteries. They remember the departed in fun and humorous ways, tell stories, make up poems, and humorous pictures.
If Blizzard wanted to expand into non-US focused holidays. This one could present an interesting twist.