The templating is wrong (I'm not sure if replacement effects can be used in costs), and the creature types and CMC P/T are all random, just focus on the idea.

The idea is, a creature like this can be used to cheapen "sacrifice a creature" costs on fortifications. I considered having a slavemaster grant this ability to another creature, but decided this was the simpler implementation, we can always do slavemaster variants as well. If there are enough "sacrifice a creature" fortifications, and enough creatures like this, the link could emerge naturally.

It's similar to persist -- in fact, the right answer might be to bring persist back instead of thinking of a variant. Currently the difference is, firstly, we can be more liberal with this as it only cares about sacrifice, not death, and secondly, it can be worked to death three times, not just twice.

What if it read like this?:

Whenever you sacrifice ~, put a 0/2 Centaur Minion token into play.

I've been avoiding token creatures because of green... but I've also been avoiding +1/+1 or -1/-1 counters because of it as well. That green is pretty hungry for counters. I don't think there's a real reason to take token creatures away from the other colors, however... it isn't green's thing. On the other hand, if there was any set that advocates the use of both +1/+1 counters and -1/-1 counters, it would probably be this one. -1/-1 counters are a logical way of stopping things from being fungus... and these five mini-planes don't really know each other, so it feeds the "doesn't happen on the same world" rule.

Yeah. I think having +1/+1 on green, and -1/-1 on black is a possibility (not a very good idea, but normally it's not even a possibility). No, wait, green probably still wants to put +1/+1 tokens on black creatures so maybe it doesn't work unless we can retemplate.

I like the "-1/-1 counter" version a lot for flavour reasons, which is where this card was originally coming from, but I agree we often have to compromise, and the other possibilities (including mechanical stuff like being able to unearth the creature once without haste, or something) work equally well mechanically.

By comparison with Penumbra Spider, I think the token could be a bit bigger. I also don't like the token being some irregular size that's precisely 1/1 less than the original creature's size: because that feels like an inferior version of persist.

Funny thing is, I kind of like the 0/2 token. You're spot on though, Alex. If this card is put in the file, it will probably have the same stats after sacrifice.

Sorry, one thing I forgot to say: I do think that jmg's version "When you sac ~, make a token" is a lot more suitable for common than something that plays directly with what effect sacrificing has.

I hate editing other people's work, so you'll have to forgive me, but if we're to move forward I got to do it.

Changed Long-Suffering Slave's name to Pressed Centaur Clan, made a 3/3 and sacrificing creates two minions. The flavor now is that this long haggard centaur tribe has managed to stick together, but if you sacrifice one of their number, they break and the other two become faceless minions. That's got to be the saddest card I ever helped design...

Changed this card to the CCC because I didn't have a CCC set aside to add to the file.

Switched cc with Dread Gorgon because of manacycling, mentioned there.

I only got this to happen once, but it was satisfying when I sac'd it to "serve through death"