Luck
Luck is a magical buff applied by various spells, items, and a single Bless effect. No one is innately Lucky. Luck of this sort extends the holder's battlefield life, by making any hit that would kill them miss 75% of the time.
Luck can only save lives. Luck cannot be applied to Inanimate beings, and it can't be applied to the technically-living Undead (such as Ghouls).
Luck also works against spells, even area-of-effect (AOE) ones. However, instakill effects generally leave no room for Luck:
- Losing a Magic Duel (since the astral host demands at least one death)
- Being Disintegrated (since surviving being turned into dust would be ridiculous)
- Being Soul-Slayed (since the body is technically still alive afterwards)
- Failing to resist Banish Demon (since the body is sent to Hell, not killed)
- Turning into a puddle of goo due to Liquify (see Disintegrate above)
Luck is a Glamour effect. The vast majority of Lucky items require Glamour to make, though 
1
1 mages can also make one. There are four Luck-bestowing spells: Personal Luck (Thaumaturgy 1), Luck (Thaumaturgy 3), Group Luck (Thaumaturgy 5), and Battle Fortune (Thaumaturgy 8). The first two require just 
1, Group Luck requires 2, and Battle Fortune requires 4 and 2
(or 3 and 3).
Not to be confused with 
Twist Fate, nor the 
Luck/Fortune Scale.