Sometimes binds a captive to you as a familiar.
A glass vial containing blood closed with a cork and labeled with a paper tag.
During capture time after a battle you will have a chance to bind a captive of that battle to you as a familiar. This is one of two items that can be used to bind captives. If there are 2 or more units avaliable for capture after the fight, only one Blood Meal is needed for the chance to capture all of them but the chance happens individually to each creature.