Even though most of the site say that you unlock a subclass at level 15 they'd be wrong. You can select a secondary class at level 12 by talking to the sprite at your house you can also change your subclass at anytime from the sprite.

This guide is still a W.I.P passive skills and active skills are still too come.

Shadow Mage (Arcanist + Dark Knight)
LMB:
RMB: Resonance Blast
1: Unstoppable Twilight
2: Disastrous Impact
3:
4:
5:
Passive 1: Insightful Advantage
Passive 2:


Sorcerer (Arcanist + Engineer)
LMB: Infinite Heat
RMB: Arcane Catapult
1: Supporting Twilight
2: Wind and Fire
3: Spherical Frost
4: Surrounding Shield
5:
Passive 1: Vulnerability Analysis
Passive 2: Potential Squeeze


Battle Mage (Arcanist + Knight)
LMB: Frost Spread
RMB: Blessing Impact
1: Alberic's Breath
2: Lightning Twister
3: Surrounding Shield
4: Seizing Hand
5:
Passive 1: Cold Embrace
Passive 2: Vengeance


Monk (Arcanist + Priest)
LMB: Blessed Tide
RMB: Introducing the Sacred
1: Timeshift
2: Ancients Of Mu Healing Light
3: Lesson of the One Inch Punch
4: Harmonic Arc
5:
Passive 1: Enlighten
Passive 2: Inner Peace


Tempest (Arcanist + Ranger)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:

Sorcerer (Engineer + Arcanist)
LMB: Infinite Heat
RMB: Arcane Catapult
1: Supporting Twilight
2: Wind and Fire
3: Spherical Frost
4: Surrounding Shield
5:
Passive 1: Regular Maintenance
Passive 2: Potential Squeeze


Occultist (Engineer + Dark Knight)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:


Commando (Engineer + Knight)
LMB:
RMB:
1: Grapple Device
2:
3: Gas Device
4:
5:
Passive 1: Going in Equipped
Passive 2:


Alchemist (Engineer + Priest)
LMB: Purge
RMB: Propelled Grenade
1:
2:
3:
4:
5:
Passive 1:
Passive 2:


Skirmisher (Engineer + Ranger)
LMB:
RMB: Tracking Grenade
1:
2:
3: FireWire Boomerang
4: Hidden Booby Trap
5:
Passive 1: Strengthened Sight
Passive 2:

Shadow Mage (Dark Knight + Arcanist)
LMB:
RMB: Resonance Blast
1: Unstoppable Twilight
2: Disastrous Impact
3:
4:
5:
Passive 1: Insightful Advantage
Passive 2:


Occultist (Dark Knight + Engineer)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:


Reaver (Dark Knight + Knight)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:


Dark Priest (Dark Knight + Priest)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:


Assassin (Dark Knight + Ranger)
LMB: Poisonous Cure
RMB: Cry Strike
1: Hate Trap
2: Corrosive Feast
3: Inverse Feedback
4: Badlands Trail
5: Diffused Curse
Passive 1: Vicious Sacrifice
Passive 2: Turn the Tide or Detached Suffering

Battle Mage (Knight + Arcanist)
LMB: Frost Spread
RMB: Blessing Impact
1: Alberic's Breath
2: Lightning Twister
3: Surrounding Shield
4: Seizing Hand
5:
Passive 1: Cold Embrace
Passive 2: Vengeance


Reaver (Knight + Dark Knight)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:


Commando (Knight + Engineer)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:


Paladin (Knight + Priest)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:


Assaulter (Knight + Ranger)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:

Monk (Priest + Arcanist)
LMB: Blessed Tide
RMB: Introducing the Sacred
1: Timeshift
2: Ancients Of Mu Healing Light
3: Lesson of the One Inch Punch
4: Harmonic Arc
5:
Passive 1: Enlighten
Passive 2: Inner Peace


Dark Priest (Priest + Dark Knight)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:


Alchemist (Priest + Engineer)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:


Paladin (Priest + Knight)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:


Druid (Priest + Ranger)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:

Tempest (Ranger + Arcanist)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:


Assassin (Ranger + Dark Knight)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:


Skirmisher (Ranger + Engineer)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:


Assaulter (Ranger + Knight)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2:


Druid (Ranger + Priest)
LMB:
RMB:
1:
2:
3:
4:
5:
Passive 1:
Passive 2: