Guildhall in the middle does the guild transformation (join guild), it does create the guild sigil (spawn creature), it has the upgrade reactions (unlock next extension), and thats it so far.
I thought about "challenges/requests". Its a free reaction that creates one item that is needed for a reward reaction, but only if you have the necessary other ingredients.
"The Masons Guild calls for 25 stone tables." - times out in 1 month.
If you manage to get 25 stone tables together, and that request item, you can bring everything to the Masons guild, get a huge reward. If you are too late? Too bad, you are stuck with all those tables.
IndigoFenix made something like that in his Mario mod, and I talked to him about importing it into MDF, but it never felt right for dwarves.
I also thought about map-wide spells/effects, similar to what Warlocks have. Each new guildhall would add one new reaction as well, but I havent spend much thought on those yet.
Another thing would be skills. A guild could automagically train a member to a set skill level, for example a Masons Guild level 3 can instantly add masonry, mining, stonecutting and architecture level 3 to any human you have. Kinda like the dwarven library works. So a level 5 farmers guild adds 5 levels of farming to everyone who can afford it.
But I want to put skill training in the universities, which is much neater.
But I am open to all suggestions. What would you put in there?