Best way to get a martial weapon using cleric in 2014 rules? I'm thinking its dwarf or hobgoblin with something that gives you access to shillelagh

>level 15 LIFE cleric
what are my chances at fighting a martial who is immune to level 6 and below spells and effects? whats my best strategy available?

I'm thinking, target his wisdom save (+1.) with a high upcast of spirit guardians + dodge. or his kind of subpar con (also 1, so a total of +6.) with Harm? but that's expensive.