Equipable in action slot.
How about you get a cheap pair of fright vision goggles by starting the game on Halloween.
The cheap pair lets you see your own Halloween items.

You get a fancy pair and the Polter-Pack by crafting empty ghost hunting gear with nightmare fuel; found in Halloween gifts.
The fancy pair lets you see everyone's spooky items, as well as enable Halloween health packs.

People who do not have fright vision can see your equipment, but those wearing the equipment can't; as well as their own.

As a Halloween event mini-game; you wear ghost hunting gear to search for ghosts in the dark.
Ghosts are captured by shooting their shadow out of walls, then by using the action button to suck them up into your Polter-Pack.
When a player is killed, their captured ghosts escape, and the player must be revived by touching a team mate in ghost form.
The team with the most ghosts captured when the time runs out wins.