This year's Objects with Symbols included the two from Epic Week 2014 - the portals that we had opened in the previous years were still open, and were letting goblin invaders through. The third one was new, and a surprise. After the first two had been closed, we discovered that the goblins had begun construction of their own portal. All of the symbols were trivia riddles.
The Fantasy Portal
The Sci-Fi Portal
The Partial Portal
Lore Wiki » Epic Weeks » Epic Week 2015 » Gameplay » Portals