Wing two comprises the vertical climb to the Alchemy Lab, stopping off along the way to deal with the Armorsmith (a.k.a Mrs. Smite). To the right is my mockup showing just the tower itself, with the rest of the castle hidden. The upper section can include a third, optional/unlockable boss (similar to Netherspite or Nightbane), or can have the Alchemy Lab itself be the 'top floor'.
The cramped quarters don't give a whole lot of leeway for swiveling the camera around, so people will need to stay zoomed in a bit, unless the diameter of the tower itself is made large enough. Rather than one sweeping spiral staircase going all the way to the top, I envision it to be more of a pagoda layout of sorts, similar to what Bruce Lee fought his way up in The Last Dragon. You take a stairway up a flight, fight a pack of mobs, make your way to the next stairway, fight some more. Going with this sort of setup, you could add as many (or few) trash pulls as desired to set a proper pace, and have some sections between flights where you do actually do a full loop or two around the tower, and fight mobs on the stairs.
I also like the idea that the stairs wrap around both internally, and externally. This gives you a chance to see the Baron's observatory on your loops around the outside of the tower, and could have a few scary knockback mechanics that could conceivably chuck you overboard if you aren't careful. If that's too punishing, the railing on the external staircases could be a loose latticework (that would keep you from flying over the ledge, but still allow you to see out), or invisible walls could be used to keep the people on the stairs. I've always felt that invisible walls are a lame constraint mechanic, especially in an area like the beginning of Magister's Terrace, where you couldn't leap over the 3 foot shrub to tackle the third boss directly... understandable, but lame. Again, this would only really be necessary on the external wraps, since internally, you would only fall as far as the last landing that you just cleared, and would be easily rezzable if the distance was too great to actually survive impact.
Trash mobs in these areas serve a similar purpose as in Wing 1, to prepare you for the area, and give you a feel of what you're working your way up to fight. These two encounters aren't gauntlets, though, so they don't need to be the exact same mobs you'll be up against later, and are able to be mixed and matched liberally.
A few basics:
Gnomish Alarmbots - The classic standbys from Gnomeregan, they blare and make noise, and are generally a nuisance. It would be cool if they summoned flying adds that came flying down (or up) from further up (or down) the tower. You would never need to actually engage or destroy these 'probe nests' but having them there gives the player an indication of where they're coming from, rather than just 'from nowhere'.
Flying Probes - I'm thinking something similar to the thing Han Solo blew up on Hoth, or the thing that interrogated Leia. It doesn't need to look anything remotely like those in the end, it's just a general idea to get the point across. Lots of little attenae poking off it, and it shoots chain lightning bolts and sleep darts while hovering around and being a pain in the neck.
Gnomes - various flavors. These come wearing different types of armor, and behave like the respective classes they represent. Rogue gnomes wearing leather that stealth around and stunlock/ambush, plate wearing little DK or Ret Paly gnomes that generally wreck hell, or little clothy gnomes that nuke. They can come in little packs of three or four. These make a later appearance in the Armorsmith encounter, and it would give the tower a feeling of being more vibrant to have these little guys and girls putzing around inside the tower chatting or whatever as they take a break from crafting gear with Mrs. Smite. They don't necessarily have to be gnomes, but gnomes make good little 'generic helper dudes' and who doesn't love killing a gnome or six?
Gelatinous Abberations - Mishaps from the Alchemy Lab. Experiments gone wrong. The Alchemy lab has us dealing with various debuffs, and they come color coded (more on that page's explanation). We're confronted by various colored blobs that have different debuffs associated with them. Orange ones spread diseases, green ones are poisonous, and purple ones have a curse associated with them. They give these debuffs on attack, and leave puddles of goop in their wake when they die that gives the debuff as well. Anyone dying to the debuff suffers an extra penalty, similar to the debuffs in the Alchemy Lab (read more about the debuffs there).
