There's different claims. Even I'm not sure and I've used syndromes a ton. Research is needed...
I, for one, love the idea of having C_Variations all up in the everywhere. I'm working on c_variation_infect, which causes the affected creature to have attacks that cause the victims to become permanently weaker, and causes them to instantly die if too many of the debuffs stack on them.
I'm not getting it to work though, because apparently, if you attempt to apply two different syndromes with CE_PHYS_ATT_CHANGE tags, the second one just doesn't do anything. It doesn't even overwrite the first one. Which is bollocks, because not only does it make vamps and maybe paladins immune to infect damage, but since there's no way to delete a syndrome from a creature, not even transformation, it doesn't appear to be possible to implement the way I intended, with progressive decreases to physical stats.
Anything is possible with interactions and syndromes if you use your imagination. Like, really, I'm not even kidding. They probably make a Turing complete language and you could build a dwarven syndrome computer.
For example to make a syndrome that you can also make end when you like:
Syndrome 1: Can do interaction 1, duration t+100; Target cannot have syndrome class: SYN_CLASS; Self only, free action
Interaction 1: Target cannot have syndrome class STOP_SYN_CLASS; Add syndrome [syndrome content] to target, duration t, syndrome class is SYN_CLASS; Add copy of syndrome 1 to target;
Simple loop. Now the creature will
1) Suffer from the syndrome for t phases, and be able to restart the syndrome for t+100 phases
2) During the 100 phases when the creature does not suffer from the syndrome but can restart it, go to 1, except
3) If it at that time is also infected with a syndrome of class STOP_SYN_CLASS, instead let the syndrome expire
That would work for your system. For example. Then you make various severities of the syndrome - they only need the one loop, you can have multiple syndrome "branches" and define conditions for when each one is applied.
In case that doesn't work and the timer doesn't get extended correctly (it's been a while), then:
Syndrome 0: Can do interaction 0, start:t+101, duration 100; Self only, free action
Interaction 0: [Add syndrome 1 to self]
Syndrome 1: Can do interaction 1, duration t+100; Target cannot have syndrome class: SYN_CLASS; Self only, free action
Interaction 1: Target cannot have syndrome class STOP_SYN_CLASS; Add syndrome [syndrome content] to target, duration t, syndrome class is SYN_CLASS; Add copy of syndrome 0 to target;
is sure to work, adding a step where you wait for the content and loop syndromes to clear before restarting the loop. It's obviously not optimized at all and a mess, but you get the idea.