Monstrum
All the baddies in one mod, plus some stuff to fight them

Mobs:

“Piper”:
Hellish bard that lures all away

Manananggal:
Vampiric beast that separates from its lower torso at night to feed on blood. Putting salt on the lower half prevents it from reattaching during the day, killing it. But it’s upper half must be fended off until daylight comes.

Leshie
During the day it blends in with the trees
At night it comes to roam
Silver and fire deal extra damage to it
Abducts villagers and players to never be seen again

Yuki-Onna
Ghost appearing in cold environments, has the appearance of a woman
Gradually freezes a target over time by having her in someone’s presence
She sometimes busts down doors to freeze the residents in their sleep
Weak to fire.

Compound Sin Demons
Demonic “animals” comprised of two or more sins

Wrath/Lust - Bloodlust, inspires it’s victims to enact horrors on each other. If attacked, will fly a bit into the air, to try and land in a spot safe from the attacker.
Gluttony/Greed - Materialism, literally eats anything physical if dropped. Possible design inspirations, caterpillar or vulture?
Wrath/Pride - Bigotry, this creature sees it as superior to all others and will do whatever it takes to prove it, even killing it’s own kind
Envy/Sloth - Apathy, inspires those to not do much, as they slowly succumb, even failing to care for themselves
Wrath/Sloth - ???
Lust/Envy - ???
Greed/Pride - Plutocracy, this creature hoards everything in sight and the more hoarded items, the more superior it is. Often pecks down those with lower amounts of hoarded items.




Other stuff to be thought of here. Second entry spurred this idea

Fellwolf
A werewolf who attempted to infect itself with vampirism as well, however as the 2 diseases are incompatible, it instead resulted in a rotting, mangled undead skeletal horror. However, they do have increased stats vs normal werewolves and vampires, but also their weaknesses (fire and silver) were enhanced as well, but in turn, they can only be killed by said weaknesses. Being killed by other means will result in the creature resembling itself until killed properly, but with a max of 50% its original health (so if it has say, 100 hp, it will return with 50 hp, and then if killed incorrectly again, it will respawn with 50 hp still, etc). Spawns in 2 locations: caves in FOREST biomes, as well as anywhere in SPOOKY biomes. Its very touch fills you with dread and hopelessness (weakness and mining fatigue) so it might be best to take it down from a range. If exposed to the sun, it will not burn but rather turn into a pile of bones that will resemble itself at nightfall, but it is harmless in this state but can still be killed. Has 2 subspecies
Wither Fellwolf (hellwolf?): A variant of the Fellwolf that appears in the nether rarely. It also inflicts wither along with the above debuffs. As it lives in the nether, its fire weakness is reduced, but its silver weakness is increased. It is unaffected by light
Stray Fellwolf: A variant only found in caves in SNOWY biomes. On top of weakness and mining fatigue, its claws chill you to the bone (slowness). However, it takes increased damage from fire, but reduced damage from silver. If exposed to light, it will burst into flames and die for good, unlike the other 2 types.
As all three of these creatures are undead, they can be controlled by a bold enough necromancer. However, perhaps for balance’s sake, they can only be controlled if the full set of Necromantic Robes is worn.
All three types will reuse the werewolf model/animations but with new textures
Items:

Blocks:
Various traps