In my homebrew campaign, started in '79, I created an uberlich that originally was supposed to allow me the option to deal with absent players and as a cornerstone of my world history.
The first time a player was absent the PCs noticed a line of dark clouds rolling in from the north. There was a rumble of thunder and a lightning bolt struck the absent player's PC, leaving a pile of smoking ash. This stunned the players, which was rather entertaining.
The next game, the player was there and was being told he needed to roll up a new character by the other players. I took him aside and ran a short scene and then the cloud and lightning returned the PC with tendrils of smoke rising from him.
What the scene was about was the PC was summoned by the bolt to the Emperor's palace. He appeared to be a normal human of noble bearing and seemed to just want to chat about the PC. This was how I dealt with absent players and didn't risk the characters.
The Emperor had ruled a land at a time then artifacts were created, magic spells were levels 10+ and his magically armed and armored armies were conquering the world. Well, something happened.
The Decline of Magic was a worldwide mystic event that centered on the capital city of the old Empire and radiated out causing the power of magic to become as described in the PHB. Most of the magic items used by the Imperial Army ceased to function causing them to lose often and badly. Most of the armies were destroyed as they tried to retreat back to the homeland of the Empire. This explained the proliferation and spread of so many items of magic.
Now, there had to be a reason for the Emperor's behavior. In the future of my game world, which was still flexible since it was the future, the Emperor suffered defeat at the hands of PCs. He survived but lost much power and decided he would take a desperate chance to overcome his foes. He created a simulacrum, sent it back in time and it had a special spell in his book. That was the Summoning Storm which only summoned those who were included in the spell. The simulacrum had no idea why this spell was important nor who these people were, but he still had the compulsion to cast it. The simulacrum was intrigued by the mystery and so sought information from the PCs summoned by the spell. The Emperor from the future had included the info he had on those who faced him at the final battle into the spell.
The PCs were also intrigued and some worked on the problem by testing the limits of the Emperor's knowledge. They found they could lie to him and also that he didn't recognize some PCs until aspects of their lives had changed; one character was never summoned until she had exhibited lycanthropy.
The final grouping of PCs in the future included every character created by the players in my campaign. Those that died in the course ofplay were considered to have had their lives changed by the Emperor's meddling that they were no longer alive by the final battle. At least two started working for the Emperor and a few more ended up owing the Empror a 'favor' to be determined later. This added a nice bit of tension in the background as they gained levels.
During one major run, based on my version of the Rod of Seven Parts, they traveled into the future and saw the Empreor and the final battlefield. They then traveled into the past and caused the Decline of Magic.
I never got a chance to run the Final Battle due to the dreaded Real Life changing where we were and who we gamed with. It was a fun campaign that I ran steadily for more than a decade. I'm slowly revamping it into 3e since I'm playing more now. The run I'm doing for my wife and daughter is set in FR until I get this one done.