Extreme Teraphobia

Absolute chaos, that is what the world is in now.
A wide variety of different monsters roam the worlds. They lurk in the caves or they only show themselves when night falls upon the world. There is not a theme with the monsters, they are all in this world just for a complete monster mash of different things.
The normal hostile mobs that you know are no longer going to spawn. Zombies, Skeletons, Spiders, Creepers and some others are restricted from Spawning. But Endermen are untouched. Removing the basic mobs was just to bring more attention on the modded mobs. As, there are still variants of Zombies, Skeletons, Spiders, and Creepers via other mods.
The last place you want to find yourself as it turns nighttime, is any type of forest. Or at least, have a good house ready if you plan to live in a forest. But in general, it's best to steer clear of forests during nighttime. During thunderstormsn, stear clear of traveling across the ocean. Surviving can be made easier with the new added Spartan weapons and new powerful ores which are rarer than diamonds.
While there is a lot of 'scary' monsters within this modpack, this modpack does not aim to accomplish an immersive horror experience. Rather, providing an experience for chaotic moments, fun, and some spooks.