I’m sure the art team can come up with something minimal or non game breaking. Something else to do besides the norm in-game is awesome I think! Even for a spell… …you know a little sorcery!
Scarecrow/Jeeper Creepers for Halloween!
Start with one of those skeletons that light up at the mounds of the dead, change the outfit a bit to conan-time wear, but leave the sickle, cape, plant fibers hanging out of the outfit and plant fiber hat. He fast at chasing you and lights up for extra spooky! “Oh crap here he comes!” You have a dark game(nighttime is when he spawns, give him murmurs) why not for the season scare the hell outta people!
He’s tough but If you kill him you get a recipe to make the outfit or maybe a recipe for something like one of these:
Something to hang your armor on for display maybe. If not he runs on to his next victim…
Candy Corn for the Fall!
Special smaller size one of these which come out of nowhere and attack you with ferocity and if you don’t look down you might be dead by the time you notice your attacker!
Tougher than normal fight again but might reward special dyes not normally available. They could come in packs as well. If not killed they will run off and disappear until they find their next victim.