I've been working on the raws for paragons, and I think I have them in a state where they're basically ready, so I've gone ahead and moved on to the reaction raws to create them...
This is by far the most FUN I've had writing raws in a long time.
Basically, what this means for you guys is that ritual units in tier 4 will work a little differently. In tier 3, you prayed to the elemental gods for symbols of favor, which you could use to "cash in" for a transformation into one of their units. In tier 4, you will only need a single item for the ceremony, which will be constructed once and then reused any time you wish.
So naturally, you're thinking, "that's wonderful, I can turn all of my dwarves into ritual units now!" Well, it doesn't quite work that way. Lore-wise, attempting to channel the power of one of the oldest and most powerful gods - the "originals," Visthel, Armok, Pel, Voruk, and Kogut - brings with it a significant amount of risk. Opening the portal necessary to convey an exchange of that much power leaves the invoker... vulnerable to certain paranormal and extradimensional phenomena that may happen to cross the conduit during the process.
Dwarves performing the ceremony to become a paragon of Visthel may get exactly what they want - or they may get something else. That "something else" ranges from, in the best cases, deteriorating effects on their bodies (syndromes, sickness, etc) to, in the less ideal cases, horrible curses and disfigurement which can even result in fortress-threatening catastrophes of demonic possession. Individually, all of these effects are unlikely to occur, but you never know when you send a dwarf to perform the ceremony if you'll get the paragon you hope for or a horrible accident. It will be important to plan your fortresses accordingly - putting the temple of origins right next to your main stairwell might not be a great plan.
In case you're curious...
-Permanent transformation into a paragon of Visthel.
-A severe migraine headache that persists for a few days.
-Tranformation into an elf for one month's time (THE HORROR).
-Transformation into a bunny for one month's time.
-Temporary insanity, which can be quelled by a radiant priest (new ability).
-Permanent demonic possession by a hellion.
-Permanent demonic possession by a greater demon.
-A plague, which spreads among non-blessed dwarves.