Luck
Here is one of the house rules that I play with in my campaigns. I did this to combat players getting screwed because of a bad night of dice rolling.
Luck
Luck is determined like any other score and it represents accidental fortune both good and bad. Luck is not pertinent to any class but can be beneficial to all.
Racial Modifiers: Dwarves, elves, and half-orcs –1, half-elves 0, humans and halflings +1
Ability Score /Modifier/ Luck Points/ Fate Points /Divine Intervention
1 /-5 /0 /0 /0%
2 /-4 /0 /0 /0%
3 /-4 /1 /0 /0%
4 /-3 /1 /0 /0%
5 /-3 /1 /0 /0%
6 /-2 /2 /0 /0%
7 /-2 /2 /0 /0%
8 /-1 /2 /1 /0%
9 /-1 /3 /1 /0%
10 /0 /3 /1 /0%
11 /0 /3 /2 /0%
12 /1 /3 /2 /1%
13 /1 /4 /2 /2%
14 /2 /4 /3 /3%
15 /2 /4 /3 /4%
16 /3 /5 /3 /5%
17 /3 /5 /3 /6%
18 /4 /5 /3 /7%
19 /4 /6 /3 /8%
20 /5 /6 /3 /9%
21 /5 /7 /4 /10%
22 /6 /7 /4 /11%
23 /6 /8 /4 /12%
24 /7 /9 /4 /13%
25 /7 /10 /5 /14%
Luck Point Usage: Each game session a character may expend their luck points on any personal attack, damage, saving throw, or skill check (Any dice thrown by player – excluding character building...example adding new hit points.) They may chose to spend the points after the roll is made, but before any other game action is determined. Each point expended is equal to a +1 bonus or 5%, and no more than 5 points maybe spent ant any one time.
Fate Points Usage: Each time a character is brought to below –10 hit points, they may spend a fate point to stay alive. This usage puts them out of action, but stabilized at -1 hit points (This stabilization will continue until the PC is helped.) These can also be used to negate the effects of a special critical wound. Once used the fate point is gone forever.
Divine Intervention: Divine Intervention is just what it sounds like, and will only have any effect in a hopeless situation.
Additional Note: The DM will occasionally ask for a luck ability check, and it is made by rolling a d20 + modifier like any other ability check. Be careful as these can be asked for at the most inopportune moments, as trying to determine which way a body falls – on the thin ledge or over the side into a bottomless crevasse. To low of Luck score can doom a PC. Only named villains and NPCs have a Luck score.
Hope it is useful to others.