I found that interactions seem to work differently in the new version. Their effects are not always applied. I may have missed something.
And I initially thought it's with DFHack and uses some script. Can someone remind me who wrote that mod which allowed to have "nature/technology affinity"? I thought it was part of gnomes in Masterwork.
It's not the interactions that are different, but the AI's affinity for using them. It seems creatures will only use 'friendly' interactions when having conversations, or occasionally with creatures they won't actually talk to but at about the same frequency, where before they would use it on basically every friendly creature in range. 600-1200 ticks used to be ample time to guarantee an interaction between two nearby creatures would be used, now it can take a week or more - or it might be quick and frequent depending on what's going on. This makes interaction-based 'intelligence' (for example, the kind used in Plump Helmet Man Overgrowth) much harder to create, and 'communicable syndromes' will 'spread' much, much slower. There are tricks, though; a creature in combat (possibly only lethal or no quarter combat) will throw out every interaction they have almost immediately at every valid target. The disadvantage being that they must be in combat, so it isn't exactly subtle.
I usually try to avoid using DFHack in mods, except when it's necessary, at which point I like to create entirely new, game-changing systems. Some people can't use DFHack and some don't want to, and I like to keep things open for them when possible. Or maybe it's just the way I challenge myself.
The druidism plugin is
here, although it hasn't been fully tested for DF2014. It should still work, since as far as I know animal taming is still controlled by the same flags.
I'd raise the chance in that case. Not many people venture into the deep caverns anyway, and finding a specific creature is even rarer. I'd personally would make the chances realistic so that people who breach the cavern face it once.
But thats only for Masterwork, because I'd make it an optional module. If you play with it all the time, the player might get used to it too quickly.
Maybe add a secret to worldgen too? That way a migrant might arrive with "the blessing of the old gods" once in a while.
I added it as both a secret and a curse, and increased the frequency of the creature probably much higher than it ought to be. (They are tough, even stronger than demons - but 'benign'). It should show up. The thing is that it's meant to be a late-game effect; even if you encounter the creature the chances of a cultleader actually showing up is low unless you have a decent population, and some of the effects don't show up for a few more years. My test runs usually don't last long enough to see how threatening they actually are.
Interesting thing to note - you don't even have to breach the caverns. The chances are low, but if someone's a few tiles away and behind a wall the effect can still take hold.