Oracle-based Warpriest?

[Larkas]

Good morning, fellow Playgrounders!

Yesterday, while rolling characters for a new campaign I'll be DMing, a player meant to roll a warpriest with heavy Charisma investment for roleplaying purposes. I went ahead and said, what the heck, make your casting and class abilities Charisma-based and be done with it. It will be more fun and potentially less frustrating for her. (I'm very open to these minute tweaks that won't affect game balance at all and will increase fun all around, and luckily I know enough of the game to know pretty well what will or won't break it; also, I'm well aware of Divine Protection, no need to mention it.)

But that left me thinking. What if there was an archetype that replaced the cleric part of the warpriest and replaced it with oracle, a la wizard->sorcerer/bloodrager for the eldritch scion magus?

As that isn't yet extant, I wanted to hear from you guys: what, aside from the obvious Charisma-base and spontaneous conversion, would you guys replace/change in the class?

[Greenish]

I'm not sure how well PF cleric's list pulls of spontaneous casting, especially on medium caster. It should at least get the domain spells corresponding to its Blessings as known for free.

[Larkas]

I'm not sure how well PF cleric's list pulls of spontaneous casting, especially on medium caster. It should at least get the domain spells corresponding to its Blessings as known for free.

Indeed. Makes a lot of sense for spontaneous too.

[MightyPirate]

Actually you probably want to hold off on those bonus spells known because the inquisitor gets a domain without picking them up. Your Eldritch Scion Magus gets more via bloodline at an altered rate so I would do the same for bonus spells from mysteries.
Those are a crazy potent class ability however so you'd probably have to give up at least Sacred Weapon and Armor and at least Half of the Bonus Feats. The Mysteries themselves would need a good nerfing as well just to maintain balance. As an example Life Mystery gives out Channeling equal to a cleric for a single Revelation. Fine tuning mysteries would be the hardest and most time consuming part of the conversion.
I'd also ditch Channel Energy in favor of an Oracle Curse. It's a downright vital part of an Oracle in terms of flavor so it must also be a part of your Waracle. The Haunted and Blackened curses need some reworking because they grant spells to your spell list for spell levels that a Warpriest doesn't get. Other than that this part is pretty easy.

Does anyone see any glaring balance issues with that off the bat? If so how might they be fixed?

[Larkas]

The inquisitor has a handmade spell list, the warpriest merely inherits the Cleric's capped at 6th. This means no discount spells and definitely no exclusive spells. The cleric list isn't terrible, not by a long shot, but it isn't as interesting as the magus' if capped at 6th and without enhanced spell access, via either domains or mysteries. What might work is adding the domain spells to the character's list (so he can select them as spells know, as normal), and/or automatically adding one of the two domain spells of each level for free to the character's list of spells known (at, say, levels 3, 6, 9, 12, 15 and 18). This kind of mimics the eldritch scion, and is a nice analog to the cleric's domain spells.

I don't intend to implement mysteries as is to the warpriest. They need some tweaking, and the "waracle"'s "mysteries" should mimic the blessings, which aren't quite domains. I don't quite intend to mess with that for the moment, though. That is some heavier brewing than I'm willing to do right now, and alas, I don't have a bloodrager to "cannibalize" like the eldritch scion did, for example.