Subclass,Transformation etc..

[Anemonia]

Source - l2guru.

(http://img193.imageshack.us/i/b215107bcf0f.jpg/)

When your subclass is level 75 depending on what arch type it is you will only be able to pick class skills based on that archtype. Eg. If you level a Titan to 75 when you talk to the npc and you "redeem" your subclass for the new bonuses you can only pick from Warrior Passive and trigger skills.

Warrior: Duelist, Grand Khavatari, Dreadnought, Fortune Seeker, Maestro, Titan, Soul Breaker, Berserker
Rogue: Moonlight/Ghost Sentinel, Sagittarius, Wind/Ghost Rider, Adventurer, Arbelestor
Knight: Phoenix Knight, Hell Knight, Shillean/Eva's Templar
Summoner: Arcana Lord, Elemental/Spectral Master
Nuker: Storm Screamer, Mystic Muse, Archmage, Soul Taker
Healer: Cardinal, Eva/Shillen Saint
Buffer: Spectral Dancer, Sword Muse, Heirophant, Doom Cryer, Dominator, Inspector


EDIT 1 - Additionally all Chance skills occur when the player attacks a target, all Counter skills occur when the player gets attacked by others. In both cases the chance/counter effect creates a buff that appears on the players buff bar. The buff is short lived typically around 10-30 seconds depending on what the skill is.

EDIT 2 - Passive and Enhanced Passives are Stackable. L75 Archtype Passives and Trigger skills do not stack.

EDIT 3 - Any skill can be untrained for 10,000,000 adena at the Ivory Tower NPC.