This spell is on the domain spell list for the Rune domain.
Unfortunately, it is impossible for a cleric to cast the spell without using Use Magic Device, multiclassing to an arcane caster, or using a somewhat obscure type of magic item (eternal wand).
This is because instant summons requires the item to be summoned to have your arcane mark on it. Arcane mark is a wizard/sorcerer only cantrip. No domains give access to it, including the Rune domain (that was the first thing I checked). You can't have someone else cast the arcane mark for you, because the mark created is always the caster's own mark. In fact, it's somewhat debatable whether magic items wouldn't make their creator's mark instead of whoever used the wand or scroll to cast the spell.
My suggestion is to add arcane mark to the list of orisons available to a cleric with the Rune domain. It certainly wouldn't change the power balance, and it's even thematically appropriate.
Not sure why this got moved to house rules. It's a problem with the actual rules in the game that prevent Rune Domain clerics from using one of their Domain spells.
Indeed.
I mean, leaving out your 'suggestion', it seems a problem with the rules as written.
Easily fixed in the next update, as you mention.
Otherwise, Rune Domain Clerics in PFS will be abandoning their God in droves when one of their core abilities fizzles
I'm no longer bother to post each and every of the Errata I find, because I still haven't heard a response to my question of what Paizo's editorial policy is for edits/updates. Without that framework on what could potentially be updated, it seems a waste of time to mark down each of these issues and quote it/post it to the boards.
I posted about this earlier today and they are now aware of the problem.
Ahhh, thanks. Glad someone got through, at least.