“ A land is reigned by a circle of powerful men who control every aspect of the citizen's life. This cabal changes members often. In reality, the spectres of a small necromantic covent possess and control the people in power. Since they simply possess the bodies, they can leave when old age overcomes their shells and possess a new up-and-coming noble.”
“ A secret MLM (pyramid) company that offers eternal life, but in fact it transfers the life forces of its members to those position 'above'. If you get high enough, (meaning you get enough new members) you start to enjoy the benefits. Maybe a willing sacrifice is much more effective for the transfer. But no one says, that a suddenly unwilling member, threatening to tell the authorities, may not loose it involuntarily... thus start people to vanish, and aged corpses are deposited somewhere safe.”
“ Want to avoid fighter types focusing on swords? Make Longswords and Bastardswords the weapon of the Noble class, with a death penalty for other to carry. These weapons will be ornate and finally crafted. Adventurers will be stuck with cheaply made broad and shortswords, while professional fighters might use two handed swords.”
