The Rime Heart
The CryoVerse is a cold, cruel, unforgiving place full of snow, ice, and rime. But where did all of it come from? Some say that the CryoVerse was always like this, ever since it came into being, which may be true, but not without cause. Ice, like all the other elements of the Multiverse, has a Source, that which froze over the entire Verse in a permafrost state. The Source of all Ice magic in the Multiverse is called the Rime Heart. The location of the Rime Heart itself is unknown, but it is believed to be under a thousand or more layers of unbreakable ice, constantly growing more and more distant from the world as it buries itself with more layers of ice. However, if that were true, and evidently since people have attuned to Ice at the same rate across the Verse, that would not affect the Verse's access to Ice magic. This is because of all the ice that is already formed throughout the CryoVerse, created by the Rime Heart and a conduit of its energy, lending it out into those attuned. Or, at least, that is the most common theory. After all, nobody even knows for sure what it looks like. Some believe that there may be a way to attune to Ice through means other than the natural process, though no living soul knows how to do so.
The Rime Heart, like all the other Sources in the Multiverse, was created by the Alchemicals through the first instances of Alchemy. The Rime Heart, and Ice with it, was the fourth of the five Alchemical Sources, and was claimed by one of the two remaining nameless gods, naming herself Ba'alCryo and the element Ice.