diff --git a/website/common/locales/en/gear.json b/website/common/locales/en/gear.json
index ad9743dd62..393b0e63f7 100644
--- a/website/common/locales/en/gear.json
+++ b/website/common/locales/en/gear.json
@@ -1098,6 +1098,8 @@
   "armorMystery202106Notes": "With this mighty yet elegant tail you can cruise through warm seas all the way to the horizon. Confers no benefit. June 2021 Subscriber Item.",
   "armorMystery202110Text": "Mossy Gargoyle Armor",
   "armorMystery202110Notes": "Velvety moss makes you seem soft on the outside, but you're protected by solid stone. Confers no benefit. October 2021 Subscriber Item.",
+  "armorMystery202112Text": "Antarctic Undine Tail",
+  "armorMystery202112Notes": "Glide through icy seas and never get cold with this glimmering tail. Confers no benefit. December 2021 Subscriber Item.",
   "armorMystery301404Text": "Steampunk Suit",
   "armorMystery301404Notes": "Dapper and dashing, wot! Confers no benefit. February 3015 Subscriber Item.",
   "armorMystery301703Text": "Steampunk Peacock Gown",
@@ -1790,6 +1792,8 @@
   "headMystery202110Notes": "The frightening visage of this stony helm will surely repel malevolent forces or even bad habits! Confers no benefit. October 2021 Subscriber Item.",
   "headMystery202111Text": "Chronovision Hat",
   "headMystery202111Notes": "A fine and fancy hat, with goggles that let you see through time. Pretty cool, right? Confers no benefit. November 2021 Subscriber Item.",
+  "headMystery202112Text": "Antarctic Undine Crown",
+  "headMystery202112Notes": "This frozen crown shimmers like the hidden depths of an iceberg. Confers no benefit. December 2021 Subscriber Item.",
   "headMystery301404Text": "Fancy Top Hat",
   "headMystery301404Notes": "A fancy top hat for the finest of gentlefolk! January 3015 Subscriber Item. Confers no benefit.",
   "headMystery301405Text": "Basic Top Hat",
diff --git a/website/common/locales/en/subscriber.json b/website/common/locales/en/subscriber.json
index ef9a6337eb..074c23d9e4 100644
--- a/website/common/locales/en/subscriber.json
+++ b/website/common/locales/en/subscriber.json
@@ -128,6 +128,7 @@
     "mysterySet202109": "Lunar Lepidopteran Set",
     "mysterySet202110": "Mossy Gargoyle Set",
     "mysterySet202111": "Cosmic Chronomancer Set",
+    "mysterySet202112": "Antarctic Undine Set",
     "mysterySet301404": "Steampunk Standard Set",
     "mysterySet301405": "Steampunk Accessories Set",
     "mysterySet301703": "Peacock Steampunk Set",
diff --git a/website/common/script/content/gear/sets/mystery.js b/website/common/script/content/gear/sets/mystery.js
index 156a36e859..5f5b117370 100644
--- a/website/common/script/content/gear/sets/mystery.js
+++ b/website/common/script/content/gear/sets/mystery.js
@@ -55,6 +55,7 @@ const armor = {
   202104: { },
   202106: { },
   202110: { },
+  202112: { },
   301404: { },
   301703: { },
   301704: { },
@@ -178,6 +179,7 @@ const head = {
   202108: { },
   202110: { },
   202111: { },
+  202112: { },
   301404: { },
   301405: { },
   301703: { },
diff --git a/website/raw_sprites/spritesmith/gear/events/mystery_202112/broad_armor_mystery_202112.png b/website/raw_sprites/spritesmith/gear/events/mystery_202112/broad_armor_mystery_202112.png
new file mode 100644
index 0000000000..da62bcc7b4
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diff --git a/website/raw_sprites/spritesmith/gear/events/mystery_202112/head_mystery_202112.png b/website/raw_sprites/spritesmith/gear/events/mystery_202112/head_mystery_202112.png
new file mode 100644
index 0000000000..29562705ef
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diff --git a/website/raw_sprites/spritesmith/gear/events/mystery_202112/shop_armor_mystery_202112.png b/website/raw_sprites/spritesmith/gear/events/mystery_202112/shop_armor_mystery_202112.png
new file mode 100644
index 0000000000..1652f3ccc8
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diff --git a/website/raw_sprites/spritesmith/gear/events/mystery_202112/shop_head_mystery_202112.png b/website/raw_sprites/spritesmith/gear/events/mystery_202112/shop_head_mystery_202112.png
new file mode 100644
index 0000000000..99f3fb6ead
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diff --git a/website/raw_sprites/spritesmith/gear/events/mystery_202112/shop_set_mystery_202112.png b/website/raw_sprites/spritesmith/gear/events/mystery_202112/shop_set_mystery_202112.png
new file mode 100644
index 0000000000..82fcb6d0be
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diff --git a/website/raw_sprites/spritesmith/gear/events/mystery_202112/slim_armor_mystery_202112.png b/website/raw_sprites/spritesmith/gear/events/mystery_202112/slim_armor_mystery_202112.png
new file mode 100644
index 0000000000..9ed19d5f71
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