Concept: Fighting the undead is always a matter of luck, those who get munched and turned into shambling horrors themselves, those few who survive when whole cities fall. However those who study the path of blazing slayers make their own luck and take the fight to the walking dead, not just pushing them back but destroying them utterly.
God: Halfling sun god. A pleasant fellow who warms the countryside, helps gardens grow, and just makes life more fun. The sun symbol is therefore recognized as a good luck charm among halfling warrenfolk.
Any combination of domains can be applied to concepts or gods with the appropriate description.