Here is the basic rundown of the theory known as Ball Lightning, also known as 'Fireballs' as they were reported in vintage Russia.
Ball Lightning is an atmospheric phenomenon seemingly with no explanation as to it's creation or existence. A simple Google search will reveal there is no single explanation as to what its comprised of, how it forms, why it forms, or any other scientific proof as to whats going on inside of 'ball lightning'. Modern science simply does not know what ball lightning is.
With that being said, here is the basic rundown of how this phenomenon is said to be the cause of death for the Dyatlov group in 1959.
#1. Semyon Zolotaryov of 37 years old was attached to the group of students and recently graduated youngsters in the final moments before setting off on their trip. Given his military background, he is said to possibly be a KGB agent. Not just any agent, but one that must embed himself into the group of boys/girls to do the impossible for the Kremlin... Go into the Ural mountains in disguise with a top-secret camera that nobody else must know about, and bring back pictures of Ball Lightning to study and possibly weaponize. The Russian government has to do this covertly because (insert reason here).
#2. Upon securing himself on the trip Semyon managed to convince the group leader Igor Dyatlov to take a detour. To venture off the planned route submitted to the University for verification of level III status for a top secret Ball Lightning photoshoot. Igor must be KGB also because he had to be in on it, or at least informed at some point. Why else would he agree?
#3. It was decided the best vantage point to photograph BL would be on the ridge of a mountain, in the middle of the night, and in whiteout conditions with negative temperatures. So the group followed SZs lead and dug in for a comfortable evening in the worst possible conditions imaginable.
#4. At some point during the night as if right on que and in the exact location among thousands of baron square kilometers, The BL showed up! Not only did it show up, but it parked itself right next to the tent!
#5. This event sent the group into a mad frenzy slashing their way out of the tent in what must have been a horrific panic. After extracting themselves out of the tent and destroying it forever, the group calmly walked down the slope to get away from what was so terrifying.
#6. Once they made it to safety a full mile away at the treeline, they settled next to a tall cedar tree and started a fire. The cedar tree was the ideal location for BL observation and its height offered a perfect view of the tent location in whiteout conditions as the BL hovered by the tent a mile away.
#7. While watching the BL from the height of this cedar, the group would know two things. When it was safe to risk their lives and go a mile back uphill to a destroyed tent when the BL has departed, and to watch their comrades progress in dying in an attempt to do so as Igor, Zina, and Rustem did not survive the trip. Its important to note, an attempt of returning to the tent was now possible because the BL had at some point left the vicinity of the tent as clearly seen in whiteout conditions from the top of the cedar.
#8. To add insult to injury, the BL returns only to swoop down the side of the mountain and explode close to the cedar which tossed Yuri and Yuri out of it giving them burns and aortas three times the normal size for their age. The BL has been selective in its pinpoint destruction as no signs of an explosion or burning (except Yuris leg) were recorded by anyone during the investigation.
#9. Leaving the remaining 4 members of the group alive and unharmed, they decide to salvage clothing and go further into the woods to build an improvised shelter (den) by digging several cubic yards of hard pack snow by bare hand into the side of a ravine snow bank.
#10. Some time later, the remaining 4 sitting comfortably in their den, butts in all four corners sitting on clothing articles that would later be found above and behind where the den and bodies were found, were viciously attacked once again by the BL. This time it selectively targeted them in the ravine and exploded causing their den to collapse crushing them. One injury in particular (smashed in skull) was made by snow falling... Not by being slammed against the boulder filled ravine/creek floor. Once again BL leaving no other physical evidence as to its presence.
Special notes: Even though nobody knows exactly what BL is or what its comprised of, it is said to spicifically target your hands, and face in a fashion in which may appear to be hand/hand combat wounds. It can even make it look as if your side was whacked with a 'baton' and your ankles were tied up. All the bleeding of the noses and mouths are an obvious sign of ship rats feeding on frozen tissue. Blunt force trauma is what BL does.
There ya have it folks! This BL theory from 1 to 10.
To be replaced if/when a better BL explanation comes along.