Grease is my favorite lvl 1 spell, it's trip when you cast and area denial that can trip who dare to move that space. It's useful forever.
Synesthesia from Occult, the best spell in the game in my opinion, Clumsy 3, dazzled and spell failure even if the target makes the save.
Resilient Sphere, super versatile, can protect in emergencies and can take a round of the opponent or an action and their best attack on their turn.
Lvl 1 - Thesis Feat Metamagic + Hand of Apprentice (Natural Ambition)
5 is the right amount, the problem is that Wizards have a class feat at lvl 1 that they are not supposed to have in the rulebook and the pregenerated character is using the correct rule that will come with the errata.
My player that used a Evocation Wizard did fine in the Fall of Plaguestone, because his to go spell was Grease it managed to do some fun interactions with the group.
Against Harold instead of going to him, my players did the ranged game with Grease in the middle of the room, making Harold having to go to them instead because he was with disadvantage using a crossbow against the bows and cantrips of the players, he had to take an extra action to reach them because of grease in the way.
Against the blind dogs in the rotten tree the players smoked out the animals out with a small fire and the Wizard put grease in the opening that made one of the dogs trip and then proceeded to be hitting both with Electric Arc each turn after.
Color spray was used often too, but he always prepared only one of this spell and heightened when at lvl 3, at lvl 4 he prepared hideous Laughter in the place because I accidentally slipped that would be the last day running that module and so he was expecting a boss. A small metagaming but I really don't mind.
You can only put a certain amount of content in only one book because of the number of pages, the Lost Omens Character guide already have more feats for the core ancestries if you wish more.
Anyway, you can pick lower level feats, and having more lower level feats than higher ones gives more options for levels that people play more often and the lower level feats are still options for higher level slots.
I am using the rarity tag as rewards for quests or adventures, this way even if players makes the exact same character in two different campaigns the player will manage to see that after some sessions the abilities and spells may be completely different because of the journey they passed.
Helped the remaining personal of Last Wall? They will offer a training for you access the archetype and you select the uncommon shield feat for champion and fighter now if you are from these classes.
Had a zombie outbreak because some careless evil cleric made them? After the issue you may encounter the undead ritual for zombies and the protection spell.
Increase the number of monster to 4, the fourth one is the music.
The Exp budget would be 3 skeletons of the same level than the party (the 2 musicians and the swordsman) and the music itself being party lvl +1, this uses a total of 180XP, for 7 players this is between an Average and Severe encounter, Severe for 6.
Makes the music a swarm but the size is the entire field of battle, it doesn't have the 3 actions by default only one but the skeletons musicians can spend one action doing performance every turn to increase the number of actions of the music by 1 for a total of 3 max, then you play around with it.
Example of cool stuff to do, the one action will be weak but the 3 actions devastating.
1 action - Will save or be frightened 1 or fascinated plus 1d4 mental damage.
2 actions- Will save or be sickened 1 plus 2d4 mental damage.
3 actions - Will save or be stunned 1 plus 4d4 mental damage.
And when all the musicians are destroyed that "swarm" is destroyed as well.
If you want to be doing damage your build is fine, Heavy Armor and better armor proficiency means that you have the same AC as an Heavy Armor Fighter when you are under rage and clumsy 1 at lvl 20 (45AC).
But from what I see you want to tank by occupying a large amount of space on the field and stands in between the enemies and your allies while swinging a big sword.
So in respect of your concept of blocking stuff with your big body what about what about Wizard/Druid/Arcane Primal Sorcerer dedication instead of Barbarian? You get access to the enlarge spell that have the same number of actions as Giant Stature (one to rage and another to get big against the two action activity enlarge) and you can get access to being big earlier, at lvl 6 and at lvl 12 you can be huge, get an Staff of Transmutation to help being larger more times a day. Bonus points you get Shield cantrip depending of the dedication.
I would suggest stop at expert spellcasting + breath for lvl 6 spell slots, Smite Evil is good to get if you are going blade ally.
I am not with the PDF here so I can't give exact numbers, so I will appoint the most glaring errors.
Saving Throws are only 3, Reflex, Fortitude and Will.
The attacks looks fine, I would just increase the saving throw a little, to 20 or 21.
The amount of damage of the abilities looks good too, but maybe add one more effect to the Cursed Tendril, like bleed or an actual curse.
Your encounter would be between Moderate and Severe, with that amount of players that would be 160xp worthy of creatures, with 3 creatures that could be:
2 Skeletons lvl 3 and 1 lvl 2
1 Skeleton lvl4, lvl 2 and lvl 1.
I like the last one better, this way the party can making the encounter easier for them by killing the weaker to stronger.
The lvl 1 one you could use Goblin War Chanter as base and add something from the Bard, change stats as you see fit with the monster creations rule, the lvl 2 use the stats of the first skeleton but add +1 to everything.
Don't forget to add the weakness and resistance usual for Skeletons and one skeleton ability.
The last one make using the monster rules (I would personally just use Gnoll Seargent stats...), an physical attacker template will do. The stronger skull toss could just work like something similar to Dirge of Doom, the players can't reduce the frightened condition while the head don't return to the body.
Don't use the highest values in the tables for this encounter or will only lead to frustration (for the players).
Halfling if going full optimised, it lets you get 18Cha/16Wis/14dex/12Con at lvl1. Lvl 5 used the Halfling ancestry to steal human natural ambition for Dangerous Sorcery.
Get Druid Dedication with Storm and at lvl 4 Order Spell.
After that get the Elemental Blast at lvl 10, Refocus 2 at lvl 12, Effortless at 16 and done, all the other feats are basically free to pick.
Sorcerer because Dangerous Sorcery and Blood Magic increases well the damage and indeed take Druid Dedication, because both use primal DC and spell attack roll the proficiency will be the same, take Tempest Surge of Druid because 1 action for clumsy 2 is great and makes you more likely to crit your spells.
Wizard and other prepared casters don't have the same restriction of spontaneous casters that can't get more spell slots or cast 10th level outside of the lvl 20 feat that gives a second spell slot, this means that a Specialist Wizard will technically have 3 spells slots at the moment that reaches lvl 19 (Drain Arcane Bond, Specialist Slot, normal slot).
That is really right?
Goblin Scoundrel Rogue
Irongut Goblin Heritage, Junk Tinker or City Scavenger to start sounds that fits better for your backstory, Street Urchin for background.
Lvl 1: Trap Finder
The rest will depend in what you want, if you want more Liberator, get the Basic Devotion for a Domain, Blade Ally Blade and get Smite Evil at lvl 12.
If you want more Roguish, just get the good Rogue feats like Skirmish strike and the deception ones, Healing Touch from Champion might be good too.
Champion or Monk looks what you are looking for.
Champion will let you try the Focus spells, shield mechanics, can use all martial weapons and have shifting rune as class feature, letting you test lots of weapons without monetary cost. Because that Champion have natural progression in Divine Spells DC you can easily get good spellcasting with Cleric or Divine Sorcerer.
Monk can give focus spells as well and is more likely to match with your background, you will play with stances here and can get shield block with a single feat. Just like the Champion, Monk have natural progression in Divine Spells or Occult so multiclassing in Spellcasters of that tradition is good too.
Spells that you already have in your repertoire and you prepare with Arcane evolution become a signature spell for the day.
Spells that you prepare that are not in your repertoire can be prepared in any spell level that you can cast, so you could prepare like Haste at lvl 7 instead of lvl 3 to target more people.
Occult Evolution is the same you can put the spell at any level you can cast.
First some background, I came from D&D 5e and with that I am having to adapt and homebrew stuff for my players that like some races and subclasses from the previous games that I was the game master, I already did the Dragonborn and have plans to do the Goliath in the future.
But for now I am making the Aarakocra, the flying
This is what I tried so far:
Similar to the elf but with 2 less Hit Point at level 1 and slow ground speed but with unlimited flying at lvl 1.
Higher Ancestry hit points but with an extra flaw, more bulky at lvl 1 but worse at the long run.
Other stuff that I thought was remove the flying at lvl 1 and give some form of glide or feather fall, but it doens't feel quite right for it not having flying, so I would like suggestions of how to make it work.
If you are using the rarity rules, giving the cleric scrolls with uncommon spells that you think that will not derail your adventure is a good way to make them happy.
Likewise with the Alchemist in the party making some of the consumables Alchemical items that they don't have is great to increase their repertoire and make them try new stuff.
For the martials you might want to look for talismans, the Wolf Fang talisman per example will bring their attention to the Athletics skills in combat.
I would say that the best uses for signature spells is when you want the effects of different levels like Invisibility that have a good lvl 2 and 4 effect, Dispel Magic so you have the appropriate lvl.
Using the signature to have more high level spells is something that is fine too, Haste is so amazing at spell lvl 7 that you probably never cast it at lvl 3 anymore, but you keep it as signature so you can have other lvl 7 spells instead of learning it at higher level.
Wizard bad? Arcane list is the best one with the only thing missing is healing and the thesis gives them versatility or power that others can't have.
Then the feats can make them the best counterspellers, have more spells per day than any other caster and even ignore some magical resistance.
They are not perfect but they are far from bad.
Cantrips heighten automatically, meaning that they power increases every time that you gain a new spell level, so they don't use the signature spell feature.
You will use this feature in spells that you use a spell slot to cast, so at level 3 you can select a lvl 1 spell to be heightened at will and get their bônus for that.