Thanks for the feedback, guys.
Yeah, I don't mind a chance of failure or undesired results. It makes a bit of sense, what with how dwarves are.
What are the chances of success? Sometimes? Half the time? Most of the time? Cuz I've had this problem with emberlights, really, and I don't feel it's that big of a bug. Annoying, but everything has a chance of failing, you know?
It's the same as an emberlight transformation - just a boiling stone that the dwarf (or slimer, in option 3) has to inhale. The success rate seems to be somewhere between 30 and 60% on average, which is something that is just inherent in how the syndrome transfer works.
For a direct transmutation is it possible to make a creature more vulnerable to a syndrome. Again I haven't done any modding, at least not yet, so I don't know if you can do that.
I cut out the earlier suggestions from that quote for brevity's sake - I don't plan to use either of them right now, but I have made a note of them. Regarding syndrome vulnerability... it's something that has not been very well researched. There is an attribute called "disease resistance," but I wasn't able to determine anything conclusive after playing around with this for a few hours - it didn't seem to affect the success rate that dramatically (though I had an admittedly small sample size).
After a few hours of thinking it over in the bathtub, I'm actually leaning towards option #1 here, and here's why:
Option #1's primary drawback is that it won't always succeed, but this drawback is shared with option three. Option one does a good job of preventing undesired slimers to be targeted for transformations if you simply pasture your slimers right next to the workshop. However, the strongest reason for why I am choosing this option is the existing layout of the workshop itself - which looks something like this:
10001
01110
00010
01110
10001
The numbers represent block tiles. Since the work area is right smack in the middle, the only approach to the work area is from the entrance on the left, and the workshop's corner block tiles make placing it in the middle of a road impractical. Because of this layout, it would be somewhat difficult to get slimers into the right position for an option #3 transformation without putting them in a very small pen, which causes its own problems when they reproduce and start killing each other.
Since there is always going to be a dwarf at the work location when the reaction completes, I'll be targeting him with the syndrome and using the syndrome interaction to transform a nearby slimer (within a few tiles, let's use three as an arbitrary number). Regardless of how many slimers are around, the dwarf can only turn one of them into a mantis.
The only remaining opportunity for exploits is if a player were to jam a large number of dwarves into the space around the workshop, potentially hitting more than one of them with the syndrome. What I like about this option is that this exploit forces dwarves on top of each other, where they can socialize, meaning that attempting to intentionally abuse this exploit often puts you at a greater risk for tantrum spirals down the line - which may or may not be a good enough reason not to do it, but is certainly worth considering if you want to abuse the system.
So basically, you'll want to pen your slimers in the area right next to the workshop, where the worker will pass when he completes the reaction. I'll be sure to note this in the manual.
...And with that, all that remains is testing and balancing those damned ritual interactions, but don't get me started on that.