Shadow Chest, Terraria Wiki

Shadow Chests are chests found rarely in The Underworld. These can contain semi rare and powerful items such as the Sunfury, Flamelash, Dark Lance, and the Flower of Fire. To open a Shadow Chest, the player will need a Shadow Key, which can open an unlimited amount of Shadow Chests without being consumed. Once a Shadow Chest is unlocked and emptied, it can be picked up after being broken down with a Pickaxe. Shadow Keys can be obtained from chests in the Dungeon, or rarely in underground chests.

I found this in a shadow chest somehow : r/Terraria

shadow chests in the underworld have new items : r/Terraria

really cool and epic shadow chest rng : r/Terraria

terraria - How does the distribution of ores & chests change with

Terraria 1.0.6 -- Shadow Chests how to get Sunfury, Dark Lance

No Shadow Chests in the Abyss? : r/CalamityMod

Cannon - Terraria Wiki

PC - Shadow Chest spawned outside 'explorable' map

The Underworld - Official Terraria Wiki

Working as Designed - I think I found a balence breaking oversight

Bathtubs - Terraria Wiki

Steam Community :: Guide :: Ornate Shadow Key Seed