The most important information when dealing with a bloodfiend infestation is knowledge of their weaknesses. Not all of us are battle-hardened warriors or mages with devastating magic, so to survive we must use our wits!
We tested several different delivery methods of fire. We found that mundane and magical fire by itself is not sufficient, but covering a bloodfiend in oil and lighting it is extremely effective. We recommend retreating to the nearest castle for this purpose, as they have oil in quantity and murder-holes to pour it from.