Luck is a powerful trait that gives units a 75% chance to evade any damage from external sources that would otherwise kill them.

Luck is largely an Astral buff, given by:

• The Personal Luck spell, which requires 1 and only Alteration 1 but only affects the caster,
• The Luck spell, which requires 1 and Alteration 3, affecting one tile of friendly units,
• The Battle Fortune spell, which requires 3 and Alteration 6, affecting 5 tiles of friendly units for 1,
• The Will of the Fates spell, which requires 4 and Alteration 8, affecting all friendly units for 4,
• Several Magic Items, which only your Commanders can use,
• And the Luck Blessing, which requires 9 Bless points and 2 on your Dominion scales, and which effects all of your Blessed units while your Pretender is awake and alive.

Undead and Inanimates are unaffected by luck. In addition, a unit with Cursed Luck temporarily does not benefit from Luck. This effect can be caused by the Fateweaving Bless, Luck's counterpart.

Luck is amazing to have on chaff (small frontline troops who you don't count on living) and is a decent layer of protection for your weaker Commanders against ranged attacks. You shouldn't press your Luck too hard, though.