Do you use a luck mechanic?

[Storminator]

I use a 3d6 roll 6's are lucky 1's unlucky
this is rolled when I (DM) have a non-DC based completely random decision to make -
never used by players.

I use opposed d20s. I roll and the player rolls. If the player wins, he decides, if I win I decide.

Frex, the rogue player wants to hide behind the ruined wall, then climb over it and jump down to attack. How high is the wall in that section? We roll, he wins, and I ask "how high do you want it to be?" I sometimes and CHA modifier to the rolls, just because.

PS

 

[Quicken]

My group uses a custom system we came up with back in 2nd edition (after the DM got sick of fudging rolls)

Every player has 'luck' points as 5d4.
You can spend luck points to adjust a dice roll. 1 point adjust it by 1 point but not beyond what that dice can roll. For instance if you're trying to kill a tough opponent and roll a 19 you may add 1 luck point to make it 20 (automatic hit and in with a chance to do critical). You can also adjust rolls the DM makes but rarely can see the dice result before you throw luck points at it.
Your luck points jump back to their original quota when you level up.
"You need to fill your bag of experience before you empty your bag of luck" - An expression I've heard pilots use about air training

It's worked well for us and has carried across to other systems nicely too. It's very useful at those low levels when you can easily die but not too useful (and deliberately so) at higher levels

 

[yennico]

No luck, no action points in our games

ditto