The lot has been cast, and my quest decided: the PRIMEUMATON spake that I must "Breathe New Life into an Old Post". So I shall, and This post seems apt for my Mazes and Minotaurs game.
Fate
The Fates sit before their hearth at the center of the world (which is everywhere), spinning, weaving, cutting, mending, all the twistings of the lives of men. They do this at the behest and consent of Zeus, king of the gods. Of course, he commands them only because he is fated to. Who can search out the workings of the gods?
All the gods (including rather minor ones) can reveal fated futures to men, and especially to their priests and special oracles (which can sometimes include horrible beasts like harpies or sphinxes). It is a bit of an effort. Way easier to just tell them things that were or are, rather than will be. Further, there is a difference between a thing prophesied and a thing fated. Prophesies can be conditional: You will surely die unless you eat that berry. Fates are absolute: You will kill your father and marry your mother.
The conditional nature of prophesy is not uncertainty in the future: the Fates know your future, inexorably. It's instead the choice of the god giving the prophecy to not give you the full story. They're still truthful, and probably more useful than a fate. But if you choose to eat the berry and not die, that was your Fate from the beginning. If you don't eat it and die, that was your Fate from the beginning too. But the god isn't telling you which one will happen.
When a character levels up, they roll to detemine if their Fate has been decided. Roll 1d10, minus the magnitude of their luck modifier, whether positive or negative. If this result is equal to or under their new level, their Fate is decided. A table of fates is given below, which can be rolled by the DM, modified by the character's Luck mod. Or the DM can simply choose which one they have. The gods have been known to play dice, but they aren't bound by them.
Example: Alexandros and Boops (it means "ox-eyed") level up to level 2, and have a luck mod (after ability enhancements) of +1 and -1 respectively. They both roll 3 on their d10 roll. The magnitude of both their luck scores is 1, so they both subtract 1 from 3 and get 2, which is equal to their level. Then, the DM rolls for their Fates. Alexandros gets a +1 to his result here, whereas Boops gets a -1 to his.
Fates (2d6)≤2. You are going to (or have already) wronged the gods, and will die an ignominious death and have one of those special ironic punishments in hades.
3. You shall die by the sword. Which probably isn't news to you.
4. You shall die by your child.
5. You shall die in some circumstance (1d6):
1. Fire
2. Water
3. Under the earth
4. In the sky
5. On the horns of a bull
6. Due to Bees.
7. Roll again. If you roll this result again, treat it as 8. The result of the second roll is complicated by the following factor (1d6):
1. You shall come within a hair's breadth of this fate, but it will not happen.
2. This fate will only come after you have wandered nearly the whole world
3. This fate will only come after you have lost what is dearest to you
4. This fate will only come if you devote yourself to one specific god.
5. This fate cannot come to pass until a certain person or monster is dead
6. This fate is surely impossible, and can be safely ignored! (until it comes down on your head)
9. You shall learn a great secret.
10. You shall wage a war against [City-state] and win.
11. You shall found a great city.
12. You shall ascend to godhood.
(results 2-5 are "Fated Deaths" while results 8-12 are "Fated Quests")
While you possess a Fate, you cannot die until it is completed. You could be chopped into pieces, turned to stone, cast into the pits of Tartarus, wither until you become a grasshopper, etc. but you can't die. Mechanically, this means that while you could be incapacitated by damage, and "die", effects such as a Nymph's Kiss of Life or a Mithraic Priest's Divine Resurrection have no time limit to work on you, since you aren't technically dead (just mostly dead, and therefore slightly alive). You can also be raised by divine intervention, or even minor intervention (Thanatos will recognize there's been some sort of a mix-up, and bring you back).
However, if you would die, instead you lose something else. This starts at the edges of your life and works in. Maybe you lose your father first, then the rest of your family, then your good name, then that magic item you use all the time, then perhaps a level, then your sight or strength... This also happens if you ignore your fated quest for a year, or do something drastic to avoid a fated death (such as trying to kill your kid). At any time you may declare that you have "nothing left to lose". This stops the "clock" for your tragedies, but you'll roll twice and take the lower result for all rolls that don't work to fulfill your Fate, and you die as soon as possible after you fulfill your fate.
Just because you have a Fate doesn't mean the spindle of Clotho stops turning. You still roll to see if you have a new Fate each time you level up. However, while you have an unfulfilled Fate, your luck modifier doesn't affect the d10 roll (though it still affects the fate-table roll), and you roll an extra dice for each unfulfilled fate you have and take the highest result. Also, rolling a Fate from a level up doesn't tell you (the player or the character) what the fate is. You still need to find an oracle for that, and probably should do it quick before some oracular monster uses it to mess with your head.
Example: Boops levels up to level 3 while still having his fate unfulfilled. He rolls 2d10 to see if he has a new fate, and gets 3 and 8. His luck mod doesn't affect this at all, and he has to take the higher. 8 is higher than his new level, so he doesn't have any new fate.
Finally, none of the gods take kindly to being toyed with. If you use your outlandish Fated Death to do some dumb shenanigans, expect the sudden appearance of your paradoxically unborn child, or a mysterious swarm of angry bees.
