Luck is an attribute that affects everything you do in a small way, from successfully attacking to the chance of successfully enchanting an item. Mechanically, the player's Luck adds half as much to most chance of success formulas as the formula's primary attribute does.
Luck is special in that it is not the governing attribute for any particular skill. Thus, Luck never receives a bonus multiplier when you level up, and it can only increase +1 per level. Luck only affects chance of success, such as chance to hit and avoid attacks, lockpicking, and alchemy, but does not boost derived attributes such as carry weight, maximum Health/Magicka/Fatigue, or movement speed. Luck does, in theory, play a role in determining starting spells, alongside the player character's starting magic skill and willpower (The formula is if magic skill × 2 + Willpower / 5 + Luck / 10 is greater than or equal to a number). In practice, since Luck has only two possible starting values (40 or 50), few if any[verification needed — any?] character creation combinations will gain another starting spell for having Luck as a favored attribute.
Luck is very important for mages because it increases the chance of successfully casting spells and, while most other chance based endeavors have finite target numbers (for example, no lock level exceeds 100) that can be reached through other factors alone, spellcasting has an effectively infinite target height. For example: Without Luck and With Luck. In Morrowind, spells can be created that have a 0% chance of being successfully cast even if one has mastered the necessary skill. However, with enough Luck, one can increase the casting chance to any number.
Luck, however, has no effect on the quality or quantity of random loot that you find. This is an old myth that has been proven to be false.
All characters start out with 40 points in Luck, regardless of race, gender, class, or birthsign; unless they have Luck as a favored attribute (only possible on custom classes), in which case it is 50.
It is possible to max out the Luck attribute by level 51 (if Luck is a favored attribute, otherwise level 61) by sinking a point into it at every level up. As it can only be increased by 1 each level, it's best to start as early as possible if 100 Luck is a goal for the current character. While 100 luck can be obtained as early as level 31 if you have Luck as a favored attribute and use the Bittercup to increase your Luck, this can only be done at the cost of a valuable quest reward and only with Luck as one's highest-raised attribute at the time of use. (you can use attribute raising spells, such as Jack of All Trades, to temporarily raise your luck above other skills and then drink from the cup for the +20 increase.)
- The Siege at Firemoth official plugin adds an artifact called the Ward of Akavir, which has a constant effect enchantment which increases Luck by 25 points.
- A creature with 100 luck is the last living Dwemer, Yagrum Bagarn (he must have been very lucky to survive). This makes it hard to hit him with attacks.
- If you have Tribunal installed, you can see the effect of Luck in combat while fighting a certain Bosmer. Gaenor's unusually high Luck of 770 in addition to his level and high armor rating makes him very hard to hit.