Foulfell Shard

This gems tracks the number of Demons Imprisoned and gives an item Corrupted quality (the count goes up by 1 for each kill the hero equipped with the corrupted item score on the following heroes: Doom, Queen Of Pain, Lion, Undying, Shadow Fiend, Shadow Demon). It was released for Frostivus 2013, and comes default on any item crafted by Recipe: Wraith King's Relic. These gems will probably be used for the upcoming spring related event at the end of January 2014.

'' Categorizing conflict: Game files label this a unique gem type (#DOTA_WearableType_Black_Gem) but uses the same value as Inscribed Gems (3). Will try to resolve when future gems are released. -Lemon''