Dalamus Ulom
Orzhov Advokist
Perhaps roll a D100, and increase your chance of success by 5 per letter rank. That way, even with EX luck, you've got at most a 30% chance of success.
And as I said before, give it a physical method of success, like rolling a D100Personally, I think Luck in an RP should only take effect in moments where everyone knows you're probably going to die, like avoiding certain Noble Phantasm types.