Krampus 1 -
Ice Puppy Pathway Somewhat easy and great level to start off the rank. Once you figure out the start, the rest is somewhat easy.
Krampus 2 -
Building festive Wafflems Clearly a tribute to Wafflem in the title as well as the design with the waffles on the right side of the level. Wow, so many buttons. Not only that, the somewhat huge level size gives the impression of a daunting level. It was somewhat hard, but it's not too hard. It's a really nice puzzle, especially with figuring out how to get both the climber and swimmer lemmings to the right side of the level. Once you manage to do that, the rest is somewhat easy.
Krampus 3 -
emmings Plus (No L) Clearly a tribute to the Lemmings Plus series by namida. I'm guessing LPI? Very tight timer but a really excellent puzzle. I kind of like this one, just the timer is very unforgiving and can be the thing to make others rage. I don't mind time limits in the game, so I'm good here. Just started getting a bit annoyed when I had the solution but I had to do it again because I released the crowd too late. The hardest part is the start due to the 99RR, especially since they're headed towards immediate danger on both sides.
Krampus 4 -
32 degrees Nepsteranheit Clearly a tribute to Nepster from the level title. This rank appears to be tributes to other level designers, especially since this is the third level in a row to reference one. It might have something to do with the rank name, but I'm not familiar with what krampus is. Not a hard level, just very fiddly and difficult to pull off because of the pixel precision needed. Ugh!
Krampus 5 -
I'm Dreaming of a GOLD xmas Very easy. Probably the easiest level in the entire rank. I have a lot of skills leftover.
Krampus 6 -
A simple kringle climb, right? Somewhat difficult but a really good level! I really like this one

It's fun watching the solution come together.
Krampus 7 -
Gift Box Gibberish Yet another no builders level. This was a bit difficult, but still not too hard. Similar concept and easier than Glacial 7 IMO. Wow, they're in the same position with the level number.
Krampus 8 -
New Years Preparation This one was pretty hard. Probably the hardest in the entire rank. Getting down safely is the most difficult part. It's even harder with the climber hatch, as even when you're successful in making splatforms for the non-climber hatch, there are many walls the climbers will climb up and will splat when dropping back down. The very tall level really makes it very daunting. I almost wanted to skip this one due to thinking I was going to be stuck here for a long time, especially since many times I would do well but then something catches me off guard, particularly saving the ones from the climber hatch as mentioned before. Skills are also very tight, and so the solution is extremely difficult to figure out, especially when trying to conserve your constructive skills as much as possible.
Krampus 9 -
Chips, Dips and Drips Difficult one as well, but nowhere near as hard as the previous level. I especially tend to have a lot of problems with levels that give a lot of stackers, but this one wasn't bad. Probably the hardest part was making sure no one falls into the water after digging away the pillars in the bottom left corners on both sides, as well as getting up on the top right. I kept trying to see if I could just make it with just one builder whenever possible, since I kept thinking I would run out of builders otherwise. Turns out there's more than enough builders, after getting the pickups, to use a second one in the aforementioned places. The top left also needs two builders to get up. I ended up using all the skills.
Krampus 10 -
This christmas bytes Ugh, another level with so many buttons. Luckily, this one's not that much harder than Krampus 2. I say the hardest part is getting to all the buttons on both sides in the middle. I think it's necessary to get both diggers going around the exact same time. Also I left one of the climbers trapped, as the save requirement allows one to do that and you only have enough skills to release one of them on either side.
Krampus 11 -
Gateway of Krampus Difficult no builders puzzle, but I absolutely like this one!

The huge level size makes it appear daunting. I have never seen this exit before. I simply tested it to see if lemmings would exit in the top right, and once that was confirmed, I proceeded to think through and solve the level. I absolutely love how you have to figure out each section on both the top and bottom. Skills surprisingly ran out really fast, so it's also necessary to conserve whenever possible even though they look plentiful.
Krampus 12 -
Snow Point Matrix For the final level of the pack, it's nowhere near the hardest, but it's still difficult and challenging enough as is. The most difficult section is definitely the right side, the bottom right entrance especially. The middle is also difficult. The bottom left of the middle area appears to be splat height, but it's not. The bottom right of the middle area, however, is. I definitely wouldn't think the level is as hard had I used CPM to confirm where each teleporter leads beforehand, but I rose to the challenge and figured stuff out as I went. This one's definitely harder than either of the final two levels in your 2015 Christmas pack. Again, skills look plentiful, but they all run out very fast. Especially the builders. In the end, I manage to have only 1 builder left. I surprisingly used all climbers too, but plenty of gliders left.
This level does have an issue in that the climbers from the bottom left who climb into the water which has the appearance of fire don't swim and simply walk in it as if the water wasn't there. However, when coming back from the left they do swim as usual. So, it appears that the trigger area of the water is misplaced. Even then, I still gave the climbers the swimmer skill as there's a lot of them and it certainly doesn't really break the level in any way. It's just the fire water doesn't work as intended when coming from the right.