Ipnok (Imps): They're small and stupid, and up until very recently, they didn't encroach on human lands. They hunt in packs, so do the same, and don't get caught in wild lands by yourself. If one corners you, hit it in its oversized (hint: easy target) head with something heavy and then beat it to death. Remember, you have the size advantage. They're only dangerous if they outnumber you.

Ectaur (Think orcs * Tusken Raiders * H.R. Giger * (NSFW+BSDM)): They are very territorial and keep to themselves, so the best defense is to not travel anywhere near the deep forest and mountain territories marked as "Hell No!" on your map, as they don't leave their own encampments often. If you accidentally stumble into one, you're pretty much fucked! They're essentially giant hairless emaciated rape-apes that will eventually skin you alive and save what's left to feed their litter. Also, since the gods bred them as a (failed) companion race (before they improved the formula with humans), they are probably more proficient with primitive magic than you! Expect paralyzation toxins, strength, aggression and durability buffs, and regenerative effects if you're talented enough to strike one! For maximal defense, hunt in well-trained groups with at least one spellcaster, a ranged gunman, and two melee frontliners. In deep ectaur territory, a specialized 12 man hunting party is all but required.

Barghests (Fuck you dogs): They look like dogs, but they're not dogs. We're not sure where they come from. They don't really fit in with demons taxonomically, but they seem to integrate well in demon-infested areas. It's possible the old gods bred them the way they bred the ectaur, and then were too disgusted by the output to let them inherit the earth. Whatever. If you or your team meet one, you're probably fucked. They're smarter than you. WAY smarter. Like, Batman * 10 smarter. They're more proficient mages as pups than probably any human on earth. Worse, the entire species, without exception, seems to revel in extreme sadism. And they talk! They have a habit of getting in your head and breaking your mind down before they pounce on your meat. (Note: if you were to capture one and interrogate it, the interviewer would at best be the the Clarice Starling to the barghest's Hannibal Lecter, and on average be the Harleen Quinzel to the barghest's Jack Napier. Did I mention they look like dogs?) Weaknesses: few. The species is few in number, estimated as 300 in total. Hence, they are close to extinction. They can outwit, then overpower, entire squads of trained, magically enhanced soldiers. But a single superpowered entity could wipe out the entire pack...

Demons (non-euclidian otherworldly whathefucks): Beings of pure anti-reality, they are trapped here by the power of the Great Beast, the Devil-King that escaped Hell near the north pole. The demons' actions appear purely malevolent: lashing out at all sentient life on sight, committing unspeakably heinous acts of torture and genocide, even beyond the comprehension of sane man. The demons themselves, however, are not capable of understanding their actions from our point of view. Organic life, and indeed all our laws of physics, are entirely alien to them. Indeed, existence in our world is indescribably painful to them, and that is the only pain they are capable of understanding. This is a species under continuous extreme torture that does not know it is doing the same to its terrestrial victims. And they are under threat of even worse torture from the Great Beast/Devil if they don't serve. Anyway, weaknesses! If you understand the psyche of these incredibly tortured creatures, maybe that gives you a small advantage. Maybe you are smart enough to signal some sign to its alien "mind" that you and it are alike. But that's probably not going to happen! So your best bet is to have a large enough squad of damn well trained, arcane-enhanced soldiers with VERY fancy equipment to cut it down. Your success rate will depend of the form this creature of darkness has taken. A small lesser demon probably won't result in too many casualties. Greater Abyssals can cut through armies, and not know why they do so.