Made slaves colourless as they are more a resource than actual people (to their masters). To go with Slave Pens - also plays in to other cards that ask for sacrifice - especially in black.

We should decide on what these are. I like 1/1 black creatures, this is a vote from Camruth for something else... Personally, I think they should be black. In this form they just feel like crappy Eldrazi spawn tokens.
As to creature type: I just put Thrull on my cards as a default type. It needn't be that at all. In fact, I think they should have a distinct type, though I'm not sure what yet.

This might be a weird thought, but what if the slaves are spirits? I've been having this idea of the Gorgons killing their enemies and enslaving their bodies, but what if they enslave their very souls? What if they make people not just work to death, but beyond it?

And by that I just mean the token slaves. The rest can be alive.

changed to 1/1 black minion