Listen to the Stinker Madness Episode
Watch the Trailer!
A faceless board-room guy (probably the one that fired James Gunn) is also a tree-man, octopus, tarantula with very dubious motivations, but likely he's actually the ghost of Chalton Heston, arboriculturist.
Slender Man the movie was doomed before it came out the gate. There is no way to pay this much fan service to the original creepy-pasta while trying to make a sensical story. Once you put Slender Man into an environment that must have some sort of back-story and character motivations and that old bummer, the Protagonist/Antagonist diatribe you've got no choice but to make your new horror icon look about as clever as the bird in the desk of The Wicker Man.