Outside of the Undercity (to the west side) is the Wickerman Festival. An NPC, Darkcaller Yanka, let's anyone who stops by know that the festival happens every night at 8:00 pm (according to your server).
At 8pm the Banshee Queen shows up (actually apparently Banshee-time is 2 minutes earlier than Server-time):
And she reminds everyone about the purpose of the Wickerman Festival: (She's met with many cheers of course.)
Here's more of the speech:
Children of the Night, heed your Queen's call!
I join you in celebration of this most revered of nights - the night we Forsaken broke the Scourge's yoke of oppression ! It is this night that our enemies fear us the most. It is THIS night that we show our enemies what it means to stand against the Forsaken!
Now is the time to shake the world to its foundations! NOW is the time to remind those who would enslave us that we shall never yield!
NOW is the time of the Forsaken! Power to the Forsaken - NOW AND FOREVER!!!
And then the effigy lights on fire. As he burns, piles of embers show up on the ground. If you open one you can "smear them on your face like warpaint" (nope, it doesn't show up on your character) and get a wicked Wickerman Buff. I caught the granting of the buff on screen here:
Your body does a really cool quickening kind of pose for a second there when you're zapped. The buff is called the Invocation of the Wickerman and it provides for Increased Health and Mana regeneration by 25% and Stamina by 25% for 2 hours.
The related alliance quest is to Crash the Wickerman Festival. (Beware thar 3 be Wickerman Guardians there.)