The Lethal Damp Blood Gem is a unique Blood Gem in Bloodborne's The Old Hunters DLC.
- A blood gem that fortifies weapons and adds various properties. Blood gems are especially rare blood stones that grow on coldblood.
- Blood gems are kneaded into weapons using workshop tools, but only when of matching shape.
- Most triangular blood gems have effects that provide attribute bonuses and extra effects.
- This is the only Blood Gem in the game that has the "Lethal" name.