These are small (4” or 10cms) balls of what appears to be glowing blue fire. These ball float through the air at a better than walking pace. They are somewhat intangible; they can slowly force their way through solid objects. Their appearance of rolling blue fire in a small balls allows them to give off light with no heat. In fact, they actually make the world around them colder (as they absorb ambient heat to “feed” themselves). Any place they touch is made icey cold, leaving ice and snow (depending on conditions) in its path.
The Dancing Lights of the Ice Wind (as they are sometimes known) can actually entrance those who look at them long enough. (Actually they can effect the emotions of most lifeforms who look at them long enough).
Blue Fires will often “strike at” living things by flying into them, absorbing their body heat… chilling them to the bone. The average human can take five or so attacks. However many times they will “cultivate” living things, helping them so they can absorb the heat they generate. Causing people to “get together” makes extra heat that they can absorb. They will make humans careless so they can freely absorb heat and the humans will not care while they do it. They can make couples ‘couple’ or make people giddy and dance or any number of emotional shifts at the right time.
Some more intelligent and tame ones will make light for caves and the Humans inside the cave somewhat peaceful, all in exchange for extra heat from its fire.