The event is supposed to continue till December 16, but I can't use a voucher to activate the quest. I have a tri, duo, and pri Shrine Guardian token to turn in but Tawner Morden won't give me the quest. I have completed the whole Tempered Stone quest line already, and have the full compliment of vouchers in my inventory. Chatting with Morden gets a description of the event but does not give me quests.