Fantasy Sci/fi part of a series? some horror elements; Medieval setting, monsters start to appear and begin taking over, conventional weapons can't seem to effect them, but they can easily kill the humans

[Mikeb]

Medieval setting, monsters start to appear and begin taking over, conventional weapons can't seem to effect them, but they can easily kill the humans. I recall they're led by some short ugly man who has a demon living inside him that gives the human abilities like the monsters.
Apparently the monsters, and the afore mentioned demon are from a different reality, our reality. Someone from our reality managed to open a spiritual door into this fantasy realm and came through looking for someone, and the demon followed him through, and such.
I believe this is the first or second book in a series. Rather large book as I recall.

[Lobstergirl, au gratin]

When did you read this?

[Lobstergirl, au gratin]

Mikeb, are you still looking for this or did you find it?

[Lobstergirl, au gratin]

No response, moving to Abandoned.