During the The Night of Long Fangs it's important to go looking for Syanna to start the next quest.
During the "Beyond Hill and Dale..." quest, speak to the little girl selling flints and either buy for 500 or win the ribbon in gwent. Once you give the ribbon to Syanna plant the beans and finish the quest. After "Beyond Hill and Dale..." is done finish Tesham Mutna (No explaination or spoiler needed) and then "Pomp and Strange Circumstance" starts. You have two choices in this quest either do an investigation or go directly to the ceremony. For the trophy you can go directly to the ceremony and the trophy will unlock at the end of a cinematic.