[Graeme Dice]

'Z' sends slaves into the laboratory from the currently selected commanders. When playing Mictlan I have my blood hunters in a province in a single control group, so that all that is required to pool their slaves is to click on the relevant message, then press 'Z'. The only issue is when you don't leave enough slaves in your lab at the end of the turn for your sacrificers to grab at the beginning of the next turn.

Of course, I'd really love to be able to automate this process.