Anti-Necromancer: Hell Tree

A very strange being rides in a bus, bound for a mangrove swamp, on the Gulf Coast of Florida. The being has an appointment there.
The being doesn't raise the dead, what it does is to deal with the ghosts of the dead and also with undead creatures. When the being finishes with them, they're neither ghosts nor undead.
The being leaves the bus, stops at a country store to obtain supplies and then walks along a trail that winds through a flat land.
After a bit, the being becomes aware that it's being tracked by something or someone. The being stops and deals with those who track him.
The being then walks through a mangrove swamp. The being has been assigned the task of remaining in the swamp, near a mangrove tree called Hell Tree, through Halloween night.
The armed men who track the being prove to be the least deadly of the creatures that the being must deal with during a very busy Halloween might.
The being has his wits and what appears to be a sword, to deal with the creatures that will menace him, through the night.
The sword is named Glyr and it's not actually a sword, but a living being, a demon fiercer than any that the being will face during the night.
All that the being needs to do is to survive, in the swamp, through the night, until dawn. However, dawn is quite a ways away.