⚔️Serberia

Revan asked for a review of the overpowered styles. I don't know all the nuances of the discounts, so I'll write more generally regarding cost.

Path of Metal
The "simplest" and most martial of the styles. At least, judging by the discounts and the lack of perks for mages. In my opinion, it is also the most mediocre, although I wouldn't call it weak. It has a clear focus on survivability.

Foundations of the Universe — in contrast to the abilities of other branches, which significantly increase the character's damage, the version from the metal branch greatly boosts survivability. Useful, but heavily depends on the character's health pool. And it won't make you immortal, no matter how hard you try.
Corrosion — we heard you really like loot. As it turns out, we were misinformed. It might be of interest for a pacifist character, but overall it looks strange. I would take this skill only if I had an excess of experience, and even then, it's not a sure thing.
Blood Tax — now this, together with Foundations, lays the groundwork for immortality, provided the character can deal enough damage.

The runes are decent, but nothing particularly interesting except for the improved version of Plate Armor. It should, in fact, combine very well with Plate Armor.

Path of Flame
Perhaps one of the strongest, if not the strongest style in the branch. Technically aimed at damage, but in practice it also provides a nice boost to survivability. I would either increase the cost of the abilities by one and a half to two times, or significantly weaken the effect of some of them.

Inferno — a good damage boost for any combat character, although the Burn effect seems almost like a mockery. With modifiers like these, there will be little benefit from it.
Gigaflash — Omniscience, but better and cheaper. It reliably cuts the enemy's evasion and accuracy down to the root, functioning simultaneously as both an offensive and defensive ability. Plus, it works with 100% probability. An OP ability that makes other OP abilities look weak. It would be OP even if it gave a chance to resist the negative effect. In essence, a character with Gigaflash is practically invulnerable and unstoppable in melee combat.
Nuclear Fusion — now this is the reason why fire damage is better than star damage. There is no defense whatsoever against the character's attacks; even a Mirayan regenerating full HP every turn cannot withstand it.

Not much to say about the runes — the first one is very good and provides additional damage that multiplies with Inferno, the second is a situational immunity, and the third is similar to its counterpart from the metal branch.

Path of Water
It pales in comparison to the previous path, although it is extremely effective against it by itself. However, most other styles also pale in comparison to that one. Nevertheless, it is also very good and offers a number of extremely pleasant bonuses. It has a non-obvious bonus in the form of the Valkyrie book boosting water effectiveness. It is more focused on survivability than dealing damage.

Storm — if it weren't for Nuclear Fusion, it would be an improved version of Inferno, trading Burn for Slow.
Ataraxia — the effect speaks for itself. In my opinion, it's well worth the experience spent.
Vivifying Circulation — a dream for characters from Miray. Or a descendant of Eshingir. And the ability itself is extremely effective, especially considering the immunity to injury.

The runes provide both one of the best stats and double experience. Only the immunity to water stands apart. It's worth it.

Path of Wind
If the Path of Flame makes a character invincible in melee combat, then the Path of Wind makes a character invincible at range. Given this feature, it's an extremely good choice for mages or archers.

Gust — for a melee character, it does roughly the same as the Path of Flame, but worse. Nevertheless, even in the hands of a melee character, it cannot be called weak.
Freedom — it seems good, but it also requires such an investment of experience that the character won't have time to use the new points.
Deflection — an excellent skill if you want to laugh in the face of a Gungnir wielding a musket. Useful, especially considering that enemies with ranged weapons usually have good accuracy. Although named bosses in expeditions are typically melee fighters.

A pleasant rune for Dodge (especially for a character from Grimwald), a situational one for immunity, and arguably one of the best runes for stats. Good, but again nothing particularly interesting.

Path of Wood
A style aimed at survivability and fighting groups of enemies. It combines particularly well with certain spear branches and shooting.

Nature's Touch — on one hand, it applies two debuffs at once, many of which can be quite nasty. On the other hand, it deals Wood damage, resistance to which seems quite common to me.
Spread — turns spearmen into sub-par archers, and archers into artillery. Like any other AoE ability, it's situational. It has a fun synergy with other AoE abilities.
Timber Terror — a decent defensive ability. It lacks the effectiveness of Gigaflash or Deflection but is slightly more versatile. Nevertheless, I would prefer its more specialized counterparts.

I can only call the first rune interesting, while the other two are not too interesting.

Path of Sun
More expensive than its counterparts and has a number of quite amusing, at least potentially, abilities.

Celestial Body — costs one and a half times more than its analogues, while its effectiveness relative to similar passives varies. Warriors get a one-and-a-half times multiplier, trading for a status effect; archers get a twice larger one; and mages exist. It deals a rarer type of damage, but the Path of Flame doesn't care.
Radiance — may not be the most efficient ability, but I like it more than the others. It not only gives two NPCs but also provides an indefinite guarantee for them. You can even deliberately sacrifice them in every battle so that Revan has to write new followers each time. Or if you don't like their builds. Or portraits. Or names.
Royal Presence — a kind of Landsknecht, but without scaling, five times more expensive, and most likely multiplies with it. I'm not sure it's worth the invested experience.

I see nothing interesting among the runes.

Path of Moon
If the Path of Sun is aimed at fun-loving guys, then the Path of Moon is aimed at terminators. One of the main competitors of the Path of Flame in this field.

Lunar Scythe — like Celestial Body, but with Moon damage.
Eclipse — a kind of hybrid of Gigaflash (lacking offensive potential, but without range limitation) and Ataraxia. Gigaflash will, in most cases, be more effective against melee attacks, while Ataraxia is better against negative effects. Nevertheless, it's a very good skill.
New Moon — like Ryoei's enhanced medal. A good ability, although very expensive for its effect. Clearly not the highest priority skill in the branch.

Among the runes, the potentially broken experience bonuses (if the ability ever works) and one of the best stat runes stand out.

Path of Narcissus
One of the strongest paths, but also the most expensive one. For melee characters, it is largely duplicated by the much cheaper Path of Flame, although the latter lacks social abilities.

Comet Fall — like Celestial Body, but with Paralysis and an even rarer damage type. An Arterian character with sufficiently high faith can duplicate the features of this passive, possibly even with greater effect, but at a much lower cost.
Penetration — when you are a budget Kasha.
Omniscience — an enhanced analogue of the Paladin ability, also ignoring the enemy's evasion. An extremely broken passive, but also extremely expensive. Due to its cost, it doesn't look very advantageous compared to Gigaflash for melee characters.

The bonus to random stats is amusing, but I'm not sure it's more effective than some runes from other branches. Except that most of the new stats will go into Speed. The immunity to Star damage is also curious, given its rarity, although it is still situational.