The feat Harmonic Spell states:
You can weave bardic music effects into your spellcasting in such a way that your spellcasting and bardic performance become indistinguishable.
Prerequisites: Bardic music ability.
Benefit: Whenever you cast a spell while you are maintaining a bardic performance, you can maintain the bardic performance for that round without expending one of your rounds of performance for the day. In addition, you can switch from one bardic performance to another as a swift action when you cast a spell while maintaining a bardic performance.
So if I am reading this right, you can maintain a performance and cast a cantrip instead of spending a performance round.
Thoughts?
Both Daze and Unwitting Ally look like good candidates. A failed will save causes a creature to either lose their actions this turn, or become a flanking buddy for your party, respectively.
/cevah
On the (current version of the) feat itself: It works, sure, but is it worth a feat? This is similar to Lingering Performance, or even Extra Performance, where the effect might be useful early on, but greatly loses value when after a few levels you usually have enough performance rounds. In combat it's only really that useful for casting centric Bards, and while it de facto grants infinite daily rounds out of combat, what are you even going to do with those? Might be interesting in a skill-centric campaign to fuel Inspire Competence, but that's about it.
The version in the Campaign Setting (and the Crown of Fangs) book is completely different, as it was written for 3.5, where the ability behaved differently. Neither version requires a spell of at least 1st level, though - that's a PFS specific change that d20pfsrd decided to edit into the feat description without any indication.
That the version in ISWG asks for "Bardic Music" rather than Bardic Performance is sloppy writing/editing, by the way.
You can weave bardic music effects into your spellcasting.
Prerequisite: Perform (any) 8 ranks, bardic music ability.
Benefit: When you cast a harmonic spell, you can activate
one of your bardic music abilities as a free action. The bardic
music is incorporated into the spell’s casting time, and the
effect of the bardic music lasts for as long as the spell’s casting
time continues and for 5 rounds thereafter. Activating a bardic
music ability with Harmonic Spell consumes an additional
bardic music use per day, but does not increase the effective
level of the spell being cast.
I could see using this for one of the bard or skald archetypes that can do X for a cost of Y rounds of performance.
I don't think one more healing from a wand is that notable, but Greater Skald's Vigor is basically infinite healing with that feat!
you could use summon instrument or some such.
Shame the duration is only min/level. I have this image in my head of a Skald singing while the party rides on, dropping a lute every 80 feet!
A Cleric(Evangelist), has the cantrips Guidance and Virtue for a +1 to a d20 and a temp hit point, respectively. While not that useful, they do help when your cleric cannot affect the opponent. [Say they are flying and you don't have range, or they have more DR than you can damage, or are otherwise impossible to hit.]
Other than this, the Bard and the Skald, do any other classes or archetypes get Bardic Performance?
/cevah
A Cleric(Evangelist), has the cantrips Guidance and Virtue for a +1 to a d20 and a temp hit point, respectively. While not that useful, they do help when your cleric cannot affect the opponent. [Say they are flying and you don't have range, or they have more DR than you can damage, or are otherwise impossible to hit.]
Other than this, the Bard and the Skald, do any other classes or archetypes get Bardic Performance?
/cevah
there's a few I was able to find
Base Classes:
Paladin (oathbound[Oath of the People’s Council] archetype)
Oracle (Ocean's Echo archetype)
Prestige Classes:
Ashavic Dancer
Argent Dramaturge
Sphere Singer
it's also worth noting that the Martyr Paladin archetype gives you an effect that is exactly like bardic performance, but doesn't actually count as bardic performance when it comes to feats, effects, etc.
Depends on how literal the prerequisite is taken. There are a bunch of archetypes that get bardic performance under a different name, including Evangelist Cleric, where it's called "Sermonic Performance". That's presuming the prereq is actually "bardic performance class feature", otherwise, no class in the game can take the feat.
Deadly Courtesan Rogue, Lion Blade if using Rogue with Bardic Pretender as a base, Pathfinder Chronicler, and everyone with VMC Bard have class features called "Bardic Performance". Exemplar Brawler's respective ability says that "feats (...) that affect bardic performance (such as the Extra Performance feat) apply to it.", which by very strict RAW doesn't help as 'applying to' and 'counting as having the prerequisites for' are different things, but I don't think any sane GM would rule it that way. Evangelist Cleric is similar, depending on how one interprets the word "interactions".
Storyteller Medium, Sensei Monk, Ocean's Echo Oracle, Carnivalist Rogue, Oathbound Paladin with Oath of the People's Council, Argent Dramaturge, Ashavic Dancer, and Sphere Singer have abilities that are stated to behave like Bardic Performance.
With this the archeologist bard can keep his luck up indefinitely, won't be able to do much else, but for that arcetype performance if very limited so this would be a pretty awesome boon.
Of those listed, only the Storyteller Medium and the Ocean's Echo Oracle have cantrips. The rest either bump spellcasting of an existing class or don't have casting.
/cevah
The d20pfsrd page links to a very old post by James Jacobs -- so old that he was willing and able to announce that the change stated in his post was official errata for Harmonic Spell.
There's either a FAQ or campaign clarification (can't remember which at the moment) that indicates that Harmonic Spell only works with spells level 1 or higher.
Found a clarification for the Inner Sea World Guide:
The feat Harmonic spell only grants an extra round of bardic performance when you cast a spell of 1st level or higher.
/cevah
I found the bard cantrip Vacuous Vessel that uses a swift action, leaving the bard a move and a standard to do regular stuff such as attacking or casting other spells.
/cevah
If you do need to cast a spell of 1st level or higher, then maybe this is something for a kineticist to dip into. Depending on whether or not using an SLA is the same as casting a spell that is.
SLAs won't cut it. The feat calls out casting a spell.
As a dip, it might not be worth it. The main Bardic Performance I use is Inspire Courage, which starts at +1, and does not go to +2 until 5th level. If you spend 10,000 gp, you can get a Dervish Sikke for your head that will bump your bard level by 5 for this, giving you a +2.
/cevah