Based on the Q&A it sounds like the Giant's Hand is only available in the Grand prize path, and the Ice Mountain Troll only in the Royal prize pass.
This is correct. If you want all four pieces of the set, you have to get to 300 presents on the normal Grand Prize path and spend the 1500 diamonds on the Royal Pass to get the piece at 240 presents. I just got to 260 presents in my Beta city, so completed the evolving building, but if I wanted the 2017 Winter Set, I would need another 40 presents, meaning I would need to spend about 3000-3500 diamonds for more keys, on top of the 1500 for the Royal Pass. This set is just not worth it, unless you have tons of spare diamonds to burn. One note is that I do buy the Royal Pass in each event on Beta because I get more than enough free diamonds there to do that, but another 3500 for the keys to get to 300 presents? That I cannot afford there.
The good thing is the better pieces are daily prizes. The Frozen Fountain, with zero extra links active, is still a top 10 mana producer and gives the same mana per square/per hour as a Burning Pool or Manta Ray. And the Frozen Orc Vortex is okay for orc production. So if you win, say 5 of each, and you set them up around your city in pairs for the one link on each, you will have really good mana production and good orc production.