Originally posted by DeathDaemon: 50% chance that a sucessful attack misses. Protects against melee/ranged attacks, whether or not they are physical/magical attacks or spells.
I don't think that it protects against spells, and if it does, then that is definetly a bug.
I was also under that impression; hard to test when something misses because of luck; but I believe DeathDaemon is right, at least according to the item/spell description.
Luck protects against damage dealing spells as well as normal attacks. However it does not offer any protection against instakill spells like soul slay.
These are good items to have and easy to get in the early game. I like to send my commanders in to melee and an item like this really tips the odds in his favor.