It's ok to do a set IMO, BUT...
If you give away 3/5 of a set, and make the last 2 buildings winable based on Luck, WHY, omg, WHY do I HAVE to win/pay for the 2 worst buildings in the set, i would MUCH rather have had 2 Rocks, and 2 Zen Zones. But then that wouldn't work, as the buildings have to be UNIQUE, why a set then, if the pieces are set?
If you make a set, i would have guessed it would be to be able to select a personal preference, but no INNO decides which building have to stand together, and if it has to be in INNO set conditions, for the building to function properly, you might as well have made it into ONE BUILDING.
The buildings look nice, but its sad that i will have to tear it down, if its not completed. The effort to get just the 3/5 and the additional Quest line, needing yet another "Research a Tech" and "Take over a Province", AND being forced to win the 2 "bad" buildings to make a functioning set, and if its not complete, its not really worth the footprint, and then you can delete it, maybe having spent diamonds to get one of the buildings, is rediculos. Was STUPID enough to repeat the Diamond use on one of the Live servers, only NOT to get the building at all, but on another server i got both the missing buildings in 3 tries.
And getting a second set, you either have to be extremely lucky, and/or cough up a bunch of Diamonds. THEN the huge problem to me would be, how many Diamonds/extra ties do i need at 25% chance to get the 5 pieces in the set, that's statistically 20 tries. That's 2.400 Lanterns, that's close to 10.000 diamonds, STATISTICALLY.
If you at least put the 2 missing buildings in the Grand prize window after the Rock, instead of a Shrine of Knowledge, and then a Well, you let us win them in daily prize anyway, base THAT on luck. If i get a Shrine i get 1 daily FP, if i instead had gotten a Pond and then the Entrance, i would have gotten +3 FP from my Gong, and +1 FP from the Entrance, and Defence Bonus, and you would have had satisfied customers. IN THAT CASE you would have gotten the set after 12 tries (Would expect the Pond and Entrance to be at 80 Flowers, like the Rock was) in the Golden Chest, no matter what you won, you would at least have gotten a completed set, and then i don't mind if the pieces in the set have to be UNIQUE.
If you base an event on luck, you have to loosen the rules quite a bit, by skipping the UNIQUE factor. If you want a Set, then let the people opting to BUY the items they need, have a SET PRICE at which, to be able to buy the pieces. Diamonds and Luck are not really what a Diamond spender looks positively at. Make it gradual like FP puchase, first piece X diamonds, and then add Y something pr. copy you purchase, then you can get as many as you can afford, and not how lucky you are. And if you then WIN a complete set, INNO has decided i have to WIN a Defence Bonus building to make it work, i don't want to win Defence Bonus, i would like to spend money on/win more Attack Bonus, and the other building i have to WIN, gives me MEDALS as its last bonus. I would have liked to sub the Entrance for another Zen Zone, as i need goods, far more than Medals, some people might feel exactly the opposite, they would choose differently, either way, the set wouldn't work.
Dangling a very nice looking set piece set, at the end of an event, maybe ending up with nothing but 3/5 of a set, having spent 20+ days, having put cities into Event mode, and solving 2 event quest lines, maybe spent diamonds, potentially ending up with an incomplete set, at least in all previous events you ended up with something useful if you finished the Quest line - NOT A FAN !!!
And then the "Two-Story Pagoda", *** FACEPALM *** WHAT a DUD "prize", if you had just spent 600 diamonds to buy a try. And 20 FP at 600 diamonds is no fun either, but at least better value, than the normal 500, NOT, should have been 25 or 50.... 5 random BP at 600 diamonds (Getting own age and lower, could be a huge dud also). Not ONE of the prizes in the Golden chest, other than the 25% prize and 200 Lanterns, is worth the 600 diamonds, but the Pagoda, takes the worst prize ever award, it can't even sub one of the Cherry Garden buildings if you didn't win the last building in the set. How tremendously unfair is it to "win" a "Event-specific" prize, going for a required building, and then the prize doesn't work with the other event specific buildings, when they all need to be set in a specific way. I've gotten 2 on Beta, and i am STILL missing the Entrance. NOT A FAN !!!