Halloween Week is a week-long event that occurs usually at the end of October or the start of November.
See main article: Growganoth
The main portion of the event is located at the special world GROWGANOTH (GROWGANOTH0 - GROWGANOTH200 are also available). In the world, the player can drop items of rarity into the Maw to obtain different Halloween-themed items. Growganoth also accepts a few special trades as well, which will always return a specific item back. As of the 2016 Halloween Week, small Eye Of Growganoths were added in the worlds, where the player will take damage as though touching a Shockinator but with increased knockback.
When items of rarity are dropped into the maw of GROWGANOTH, items of higher rarity are more likely to yield better items. Dropping multiple items of a combined higher rarity is also more likely to yield better items. For example, dropping an item of rarity 90 will be more likely to yield better results than dropping an item of rarity 80, while dropping three items of rarity 90 (in one go) is more likely to yield better results than dropping one item of rarity 90.