Help me prep choose my last 5 lvls

[Falcii]

i am currently using a spirit shaman 5/ stormcaster 10 build mostly as a utility blaster for my group (which is basically cleric, paladin, wizard, fighter). The camp is mostly RP based so i care most about flavor and utility, but id like to avoid losing to many more caster levels. Any help i could get with figuring out my last few levels would be greatly appreciated!

[lylsyly]

can you qualify for archmage with that build? 5 SLAs for 5 levels.

[ZamielVanWeber]

No Archmage (requires arcane casting and spirit shaman is divine) and sadly hierophant does not advance casting. What feats and skills do you have? Sentinel of Bharrai is cool and can fit the flavor, but sadly requires two feats.

[Rebel7284]

A Holt Warden dip seems useful for getting an extra domain slot of each level.
A Contemplative dip can be useful for access to a domain.
A Sacred Exorcist dip gives you turn undead, which is very useful for all those great divine feats.
Thaumaturgist is rarely talked about, but it's an OK class, getting a limited Contingency and a Cohort which may double your power!

[Zaq]

A Holt Warden dip seems useful for getting an extra domain slot of each level.
A Contemplative dip can be useful for access to a domain.
A Sacred Exorcist dip gives you turn undead, which is very useful for all those great divine feats.
Thaumaturgist is rarely talked about, but it's an OK class, getting a limited Contingency and a Cohort which may double your power!

Seconding Contemplative and Holt Warden, since both of them are excellent choices on a Spirit Shaman.

Earth Dreamer (Races of Stone) is a nice low-key PrC that's easy to get into and doesn't lose any casting. The only really game-changing ability comes at 5th level, but it's a nice no-fuss set of tools for a relatively low investment.

Divine Oracle (Complete Divine) mostly offers defensive abilities, but at the same time, when those abilities happen to come up, you'll be glad you have them. Access to the Oracle domain doesn't suck, either. You'll have to get K: Religion from somewhere (Knowledge Devotion is an easy way to do that if you have a free feat), though.

Stormlord (Complete Divine) is thematically appropriate, but its abilities are more suited for mid-level play than high-level play. I've played in a party with a Spirit Shaman/Stormlord, and it worked pretty well, but again, Stormlord's abilities are probably going to be a bit overshadowed by ECL 16+.

Loremaster (DMG) is pretty much never a bad idea. It's also never going to be a crazy character-defining class, but it's got a decent skill list and it can refund the feat you spent on Skill Focus. If you're cool with the Paragnostic Assembly, Paragnostic Apostle is similar—it won't overshadow the rest of your build, but it's not entirely worthless.

Of course, you could always just go back to Spirit Shaman. It does have class features, after all, even if they aren't completely overwhelming by the late game, and more importantly, it won't cost you anything (since it's a base class with no prereqs). You won't get it until very late in the game, but the level 10 class feature that lets you hand off concentration on a spell to your spirit guide is actually pretty hard to duplicate, so that's something to look forward to.