Demon incursion

As the armies of Afrya have pushed forward to the goblin cave entrance, but now the goblins have been replaced by a variety of demons. This is a report on the demon types I have recognised as well as some observations that point to the existence of a portal to the abyss.
 
A list of demons by name: Manes, Dretch
 
There are two more that I can only describe:
* A tiny creature which is bipedal with frog-like legs, a humanoid(-ish) torso, swollen back and a head I can only describe as bat with horns. The skin colour ranges from white to green.
* A human-sized creature, which stands bipedal and has long, thin hands with claws. The head had a single goat-horn on top and a mouth of a vicious predator. Once the creature knocked a soldier unconscious and immediately teleported away with a second soldier. Neither survived the encounter.
 
The observations I've made that have lead me to believe that it is a demon invasion are the following:
* Plants normally green are now a sickly brown.
* Grass is like the spines of a porcupine.
* The rain smells foul and is poisonous after only a few hours after it has fallen.
* Weather is odd, out of place for the season and rather violent.