I need to go to bed, I've been reading this and the Construction threads for the past hour and a half.
Anyway, I'll drop in my speculation and then I'll go to sleep:
I remember for XIV there was a scarezone called Point of Evil, in which a giant machine was gathering up all the fear and evil from across the the planet and concentrating it all into one point, which was at Halloween Horror Nights. A year later, a tree grows in the exact same spot. But I'm thinking to myself, what if that machine wasn't gathering fear and evil from OUTSIDE influences, but rather from INSIDE influences?
As in, harvesting whatever lied beneath said machine? Perhaps we have a situation to where the Machine was like the Gorewood Tree, gathering up dark energy from way below the surface of the Earth.
Flash forward to now.
The recent speculation of a Greek Mythology house has me thinking about one aspect of Greek Mythology in particular...Hades. The Underworld. Think about how trees get water and nutrients from its roots alongside using the sun as another source of harvesting energy. What about harvesting the power of a demonic underworld via roots from a tree? As we've seen in several instances, trees have been used as portals to another world with giant holes in them (yet I do not know the specific term for it). Alice fell inside one and landed in Wonderland. Darkness enters and leaves our world through one. In the Tim Burton flick Sleepy Hollow, The Headless Horseman did the same thing Darkness did with the Tree of the Dead.
So considering the past several houses/scarezones have taken place in the confines of the small town of Carey, Ohio, it is safe to assume that Uni Creative is basing this year's event in that very town, encompassing any and all icons and characters that inhabit the Halloween Horror Nights world. And in that small town lies the very Root of All Evil itself, the entity that has its direct connection to the Underworld and is harvesting its very energy to wreak absolute havoc amongst the human population.
I do believe we are looking for a tree. For the tree is most often considered to be very essence of life itself. The tree that lies in Carey, Ohio, however, is the exact opposite: it is the very essence of DEATH.
....'k, I'm off to bedtime now.