On my world (Antica) where there are a few Halloween house contests, here is one as an example: https://www.tibia.com/forum/?action=thread&threadid=4823364
I have actually redesigned my museum of wonders and arts to have a Halloween theme, featuring separate themes within each room. I don't know how to add in specific item animations here like other players do, so I will post some pictures of my house so you can see the items I have used and how they look in game then list those items below with some info,:
Halloween theme Museum Ground
Halloween theme Museum 1st floor
Vengothic Furniture: You can buy this furniture kit for 280 tc in store.
Ferum skin NPC with Name theme (I chose my name since it fits in well): This cost me 1050 tc to do but you can have a lot of fun with creative names/theme and not all of the skins in store cost 900 tc, They can also be switched out anytime.
Gloomy Poisonous Fungi: This tc item offers some natural purple light and was 60tc.
Ring of Ending: This item gives natural red light and has a constant spinning animation. The ring itself is also hard to get and takes a 50% chance of death to make.
Skeleton Decoration: You can get these fairly cheap, they hang on walls and you can get creative with putting buckets of blood/other items under it.
Bat: This item is really nice, isn't too big so can be placed easily with other items and has 2 animations, one which it flies in the air and glows red. 180 tc from store.
Trophy of Feroxa: Scary trophy, looks nice.
Psychedelic Tapestry: Another nice item which can be hung and actually animates a color glow.
Demonic Tapestry: Another nice item which can be hung with an animated blinking demon eye.
Skull Fetish: This is a large skull with red rune carvings.
Young Lich Worm: Small green looking worm, I placed it in a bucket of blood though there are a lot of options.
Bloody Edge: Fairly cheap and nice sword with natural blood detail on the blade.
Skull totem items: You can add items like Phoenix eggs, Skulls, trophy stand, eternal flames, and non decayable bodies to create cool looking torches/alters. Note: a good place to find a range of non decay map bodies is Edron orcs, though there are many places.
Pet Demon: Tc item for 250 tc, large item so adds impact to room and has 2 animations.
Scroll of ascension: this item is nice as it turns the player into a demon when used then goes on cooldown.
Large Pliers: This is another nice item to combine with other items to create alters or torture scenes. It is unique in that it looks like it has height like a trophy stand but it doesnt impact an items height when placed over it.
Stone Tablet with key lines: This is a quest item so a little annoying to get but it has natural purple rune carvings with a large black background that can act as a natural tile/carpet with an evil overtone effect to it.
Medusa Skull: This item can be bought with silver raid tokens/from market for around 1,5kk on my world. It is a really nice skull as its hair actually animates into snakes that move (without having to be used).
Lost Soul & Purified Soul: These items are nice to add impact to another item, especially the Lost Soul as it looks like a black glowing cloud.
Burned down firewood with Demonbone amulet: I like to place Demonbone amulets over burned down firewood to make an alter effect, the fire wood can be found in game in places like venore.
Smoking Coal: another nice item which animates a smoke or puff. This is cool to add with flames or bodies.
Odd Organ: A large tile item that is bright red, is a good background item to use with designs.
Grimace: This is a nice scream face which is scary.
Diabolic Skull: another nice scary skull item.
Bed of Nails: This is a nice item to use for designs.
Bloody Tears: One of the only blood decal items I have found which can be used for tiles/over bodies or other designs.
Bat Decoration: Really nice and can be hung on walls.
Burned out Devour Core: This has a nice natural animation and offers a glow of red light.
Flames of the Percht Queen: This is a larger flame item than the eternal flame and offers different options when designing.
Blazing Bone: another nice item for impact.
Dream essence egg: I used these to make a small magic pond look under my dragon, but these could go well with a scary spider theme room.
Cluster of Solace: This item looks like a more vibrant spider web and goes well with lighting effects and other items.
Rotten Heart: Black Heart that beats an animation. Looks really nice.
Toy Spider: Nice item, has a crawling animation when used.
Spider Webs: Nice item that can be hung on walls.
Spider Silk: Nice item that can be used for background design.
Larvae: These look like maggots which wriggle on the floor, really cool if you are creative.
Pumpkin Head: You can get these by using kitchen knife on a standard pumpkin, they can also bit lit if you use candles on them.
Witch Broom: This item in a more beaten down/scary version of the broom.
Scared frog: This is a cool item that looks like a normal frog.
Witches hat: Standard scary deco item.
Goblin Zombie Cask: You get this as a quest reward but it looks like a normal cask, though when used it animates a goblin zombie popping its head up from the barrel.
Stuffed Toad: Standard.
Panther Head: This is another scary skull/head item that can be used.
Rotten Witches Couldron Seed on a slime filled pot: The seed itself fits really nice of the pot, you can still see the liquid, so you can play around with slime/blood.
Exalted Sarcophagus: This is store item is 120 tc and can be opened/shut revealing a mummy inside with glowing red eyes.
Light of Change: TC item for 180 tc, though you can change its light impact from blue/red/green depending on the impact you want.
Carnivorous Plant: This is a nice plant with teeth that snaps its mouth in a natural animation. You can buy this for 150tc.
Glowworms: TC item that be be changed between lit or unlit. The unlit version looks spooky with glowing green worms inside.
Also, here are two before pictures of the museum of wonders and arts prior to the house of horror theme for some context:
Museum of Wonders & Arts ground
Museum of Wonders & Arts 1st floor
I was wondering what other items could I use to add to a Halloween theme house?
I see that there is a question asking what is the creepiest/scariest them house here: https://www.tibiaqa.com/17507/what-house-decorations-are-the-darkest-and-creepiest
But I am not wanting just creepy or scary, I am wanting to know what items I can use that are Halloween themed (the holiday/event itself) and not just creepy or scary items as I feel these contests will require more original thinking for Halloween itself.