Wexio Christmas Calendar 2018 Mystery Cache

Note! There is absolutely no need to write "I solved it"-notes on participating mysteries.
The picture below is also clickable....

This is a mystery cache that involves solving twentyfour other different mysteries to get the final coordinates for this cache.
Each day between the 1^st and 24^th of December 2018 I'll update the cache description sometime between 8:00 - 12:00 to let you know which cache you have to solve that day.
As you solve each of the mysteries in this series you will be rewarded with a letter when you check you solution with the Geocheckers below.
After solving all caches you shall use them in the certitude checker and then you will have the coordinates for this cache.

The difficulty of the mysteries is varied and distributed randomly.
The total sum of the difficulties is slightly over 80 stars. Some are easy, and some will hopefully strain your brain.
I have solved all of the mysteries myself (occasionally with a little help from a friend).

If you used the Certitude before the 27th of December 2018, please recheck. There is new information in the checker

You can validate your puzzle solution with certitude.