.:The Sentinel has deemed you worthy of her words, mortal...
In order to use the Bloodstone gem, go to the entrance of Dead Man's Shadow and click the entrance. You will be asked if you would like to use an item to gain entry or something like that. Choose yes. Your bloodstone gem is now soulbound and you can enter Dead Man's Shadow at any time without having to do anything special. You do not need to equip it.
"I think I'd still rather devour this world in flames while legions
of demons poke at the few remaining survivors with tridents.
That sounds more my speed.":.