Soldier,
This is to inform you that you and your men have been assigned to draining duties.
Make sure you do not waste any blood – and so, slit the victims's veins only once they have been properly positioned over collection vessels, and leave them up for at least four hours, to ensure they've been drained dry.
Once a barrel has been filled, add the specified amount of leech spittle, cork it and send it off to storage facilities.
Above all, ensure that the barrels contain nothing but pure blood. Should other effluvia pollute the batch, discard it and rinse out the barrel well before filling it up again.
Be aware that watering blood down – or any other form of tampering – is considered a grave offence, punishable by death.
Do not disappoint me.
Boyar Ambrus