[PF] Classes / Feats that Buff Allied Spellcasters?

[TC X0 Lt 0X]

Are there any classes that buff allied Spellcasters? Specifically, affecting their spells (be it increasing caster level, adding metamagic, etc).

From my cursory check, all I spotted was Magician Bard, but I doubt that is all there is.

Feats (or anything else really) are fine as well, presuming that they do not require the buffed spellcaster to take them (or the character has a way to provide the feat to the ally)

3rd Party Material is fine, though 1st Party is always preferred.

[Dastis]

Cavalier Order of the Staff
Arcane Subdomain
Channel the Gift(donates a spellslot)
Arcane Concordance
Font of Spirit Magic

Missing another spell lv2-4 but I haven't been able to find it again since I first found it

There's also several teamwork feats but they have to take them as well or you have to jump through a lot of hoops to be able to be both able to cast and give them to allies.

[Dastis]

Found it. Collaborative Thaumaturgy

[citricking]

Court Poet Skald boosts their int or cha boosting their DCs.

[Cevah]

Coven Caster gives +1 CL to adjacent caster.

Coven does the same for one in the coven.

Both gives all in coven +1 CL.

/cevah

[Trevor86]

Dawnflower anchorite prestige class. At the cost of 1 caster level you get an ability that duals as a lite version of the bard's inspire courage but also increases the save dc of all allied spellcasters by 3 or 4 (though vs evil enemies only). Increasing the save DC of allied spellscasters by 4 is a huge benefit.