I noticed a possible problem with the Rune domain. The 7th level domain spell is instant summons, but instant summons requires an arcane mark for functionality. The Rune domain does not (funnily enough) grant arcane mark as a domain spell or spell-like ability.
Heh... yeah; Jason's got an idea or two on how to fix this, but he's at Gen Con Australia right now so I can't ask him right now WHAT that fix is. Might be as simple as just giving the Rune domain the ability to use arcane mark as a cantrip as part of the domain's power. Or maybe a line added to instant summons that says something like, "If you cast this as a divine spell, you must instead inscribe your deity's holy symbol on the item."