This mods adds new mobs and mechanics to challenge the player!
First, monster mobs will have a chance of dropping Monster Heart Pieces, which can be crafted into Monster Hearts, used as a new resource for things of the mod, as Halloween Potions, Weapons, Armor . . .
Also, a new important potion effect : Halloween. This effect will kill the player if they try to sleep. On top of that, when hit, a Rotten Arm (new mob) will spawn and attack the entity with the effect. Halloween has a chance of being inflicted when waking up or sometimes by being attacked by an Undead mob. But Halloween has also some good properties! Like increasing Monster Heart Pieces chance of dropping, or boosting/activating some items, so balance it is key.
(There 2 new gamerules called DoHalloweenInNightmares, which if false won't inflict Halloween when sleeping, and UndeadInflictHalloween, which is the chance of inflicting Halloween when hit by an Undead, set to 0 to disable).
Halloween can not be cured using Milk, but can be cured using food made with a new Crop: Turnips!
Turnips can be found by breaking Wild Turnips, which generate randomly on the overworld. Also Farmer Villagers can trade Turnip-related-items.
Another new mechanic is Advanced Monsters! Monsters have a chance of spawning more powerful than usual, if they are around a 30+ lvl player. Also Monsters from this mod have extra quirks when Advanced, to make defeating them more difficult. When an Advanced Monster is killed by the player, it has a chance of dropping a Mystic Runes used in some things on the mod like Weapons, Armors . . .
(There is a new Gamerule called AdancedMonsterSpawnChance, set to 0 to disable Advanced Monsters from spawning).
There is new Villager job, the Hunter! Their job block is the unactive Vampire Artifact, found in Vampire Fortresses, a new structure. They trade some items from the mod.
And the most important part, the mobs! This mod adds 8 new Monsters mobs such as Vampires or Freepers, Creepers cold cousins. And 1 mini boss!
More info of the mobs in the ingame guide.
Very Cool