Bolts used in Crepus' Black-Key Crossbow, an assassin's tool of exquisite craftmanship. The intricate spiral tip bores deep, injecting scarlet rot far into the flesh of its target.

The following locations: 20x are found after the first Stonesword Key door in the lower level of Roundtable HoldLandmark, along with the Crepus's Black-Key Crossbow. 20x gained from killing Rileigh the Idle as part of a Tanith's questline. 20x can be found above Sellia GatewayLandmark. Can be reached by going southwest from Church of the PlagueGrace. the Fortified Manor, LeyndellRegion Royal Capital. 10x can be found in Lake of RotDungeon, southwest of Lake of Rot ShoresideGrace site of grace. Crossbows that can fire faster or more volleys at a time can better apply status effects, such as the Pulley Crossbow. Only a finite amount of this ammunition is present in game, thus these should be preserved for select encounters. The Rotbone Bolt, despite its drawbacks, is more reliable for inflicting scarlet rot for this reason.