900% luck on top of standard levelling up bonuses? I think that's a bit overkill! I was just thinking of Luck as an additional bonus to slide events to your favour, not provide uncanny God-like ability. Although I agree that my first thought might be a little under-effective, much like Wisdom was.
I do see what you're saying, though. Personally, I don't think Luck should rise automatically. You already have the Agility attribute to raise your Offence and Defence and just because you've worked at rising a level doesn't really make you any luckier. I think Luck would work as a skill. I see luck as trusting your instincts or being guided by a higher force. By developing this skill, you are learning to trust your instincts or guide to lead you to glory.
