There’s a discussion over at Robertson Games about using Luck points or the like to reduce the impact of a series of bad rolls resulting in character death. I’m not a big fan of them, preferring explicit script immunity if the game isn’t going to just let the dice fall where they may. I totally get why not every game needs to challenge the players and have character death or significant defeat be a live option, or at least give the players veto power to avoid stupid or anticlimactic deaths, but I think that Luck Points in the sense of a small finite resource than can be spent to reroll or force a roll to a certain outcome aren’t an adequate response. On the one hand, they’re too little: they don’t actually guarantee that unacceptable outcomes never occur. Eventually the party runs out of do-overs, and then they’re stuck even if another unacceptable outcome occurs. On the other hand, they do too much, since the players will almost certainly come to consider their presence (or absence if they’re running low) when evaluating their options. If you don’t want a TPK when the party foolishly attacks a sleeping dragon they happen across while on some unrelated quest, giving them Luck Points may actually encourage them to attack it; in effect Luck Points subsidize them making game-mechanically foolish choices.
Generally I prefer that the GM and players either agree in advance that they have script immunity, or they take up situations where a run of bad luck has derailed the game or killed a character on a case-by-case basis, deciding whether to live with the outcome or retcon it as an extraordinary measure. I’ve long felt it to be a mistake to roll for something if you’re not willing to abide by the roll; if I really don’t want characters to die as a result of bad rolls in combat, I take the option off the table, for instance by making less than 0 HP mean incapacitated, fate to be determined. It occurs to me, though, that it might be possible to craft a mechanic that answers my objections.
Suppose instead of a pre-figured supply of Luck Points which could be used to overrule or reroll a bad situation, you had an unlimited supply…but each time you invoked the rule you gained one Karma Point. The GM could then spend one Karma Point to overrule or force a reroll some time down the line, negating some good result you had rolled. That clearly solves the problem of a finite supply just kicking the can of reckoning down the road, giving the players a form of script immunity when it was just notably bad luck that screwed them over. It might also address the problem of the players counting on their immunity to let them try dumb things, since they would know it would cause them potentially serious trouble down the line. Yes, they could know in advance that whatever happens they can survive the dragon’s first breath attack…but at the risk of turning an otherwise easy situation later on into a fiasco. It wouldn’t anwer for players who really need script immunity so their fun isn’t all bashed out of shape by random die rolls, but it might do for players who were generally interested/willing to subject their character’s fate to the dice but wanted some measure of veto power over extremely inopportune rolls.