Well then, lets see about your class. First, I'll note I quite like the concept. It's always fun to see a dancing based class, and necromancy is one of my favourite schools of magic.
Well, first thing I noticed, on spellcraft you seem put the ranks in parentheses, while not doing so for the other skills.
Skills seem fine, they match the theme of the class.
The spellcasting progression makes me a bit wary, but seeing as you need levels in a different class from the one being advanced (even if it is a class with minor progression of its own), it may be fine.
Bardic music usage advancement fits fine.
Nice and flavourful. However, it seems you are missing the word 'that' in the second sentence.
This line doesn't quite make sense. Might want to clarify it.
Just some minor typos, but you need to remove 'a' in the first sentence, and should change class number to class level in the second.
Don't see any real problem with the non-standard DC.
I'd suggest stating this can't exceed your total level.
I might suggest making the bonus require 5 ranks in Perform (Dance) so as to better match with other skill synergies.
A fun ability, if not one likely to be used often. Might be worth expanding it in some way to be usable with willing non-dancers. Anyway, a few typos. The first sentence above should either start with 'they' or have an 's' on the end of dance. The second I'd recommend changing 'dances' to participant.
Disciplined Mind is a nice flavourful ability.
Sense the Opening Door is an interesting ability. Given the flavour of it, it may also be fitting to at some point grant an ability to easily identify creatures as living, non-living, dead, or undead.
I'd suggest altering the wording to be since the start of your most recent turn, rather than during rounds. Mainly as it currently does not grant the bonus at the start of rounds before your turn arrives in initiative order if you started or continued a dance the previous round.
I might suggest altering this to letting them recognize undead while dancing. As it is, most undead are unlikely to dance. Perhaps alter it to granting the effects of the deathwatch spell while dancing.
Last Dance is an interesting capstone, and while powerful, doesn't seem problematic given its ability to only be used successfully once.
On Age Draining Waltz, I'm not sure the use limit on specific creatures is needed, given the time required to pull it off. Then again, I may be slightly biased with regard to that, as the limit prevents the interesting idea of a Dancer dancing with someone as they gradually get younger, while the other person gradually gets older, until the ageing person eventually dies.
Only skimmed the rest of the dances, though I'l try to look them over in more detail later today. That said, it might be worth adding a feat that allows you to learn additional dances you qualify for, possibly with the prerequisite of already knowing 9 dances, or noting dances learned by the feat don't count for learning other dances. This was a Dancer may continue advancing their dances after reaching level 10.
I'll admit, I did have some trouble trying to come up with a capstone. Initially the implant seed was going to be it, but then I decided that should come sooner. I though the ability to grant others the ability to make seeds and graft them for you might cut it, but it is rather situational. Perhaps I could add the idea I'd had for a feat that would let you graft your seeds onto inanimate things like plants or walls as a capstone. As for the class features depending numerically on class level, I'd thought they mainly were based on the total graft level of seeds hosts had on them. Odd, I'll take a look at that.
Hmm, your right, the ones that mimic spells should likely be supernatural. That said, the others are more intended to show that the grafts are a part of the sower still, and as such have some connection.
Well, as I see it they could generally point to in the direction of a seed and estimate about how far it is (depending on their sense of distance). As for if the host is on another plane, I should specify that. They may tell what plane the seed is on, but not what distance or direction it is (and they don't actually know the name of the plane unless they've been there, or know it from another host of a seed going there, then coming back and telling them what the name was).
Gah, missed that. The Black Forest should be capitalized as well. I'll see to fixing it.
I suppose it is somewhat roundabout, though I'd not really noticed it. I was somewhat thinking about it more like locals assuring people there is nothing that is safe to be near in the forest.
Owrtho