There are five unique Classes available at the start of the game. Each class has 3 tiers of skills that are unlocked via use of Proficiency points.
Towards endgame, players can unlock a fourth class (Advanced Class) by fulfilling the needed elements.
As of the maintenance update on 6/7/16 there is now a second growth ring under (Advanced Classes)
"Champion of Defensive Arts"
Class Tree: Soldier → Knight → Paladin
Advanced Classes: General> Royal Protector
A tank based class which specializes in soaking up damage (including taking damage for teammates), and buffing themselves and the party.
Skills include Damage Absorptions, Defense boosts, Max HP increase, Attack debuffs and Monster aggro.
Soldiers specialize in Swords and Axes as they receive bonuses to ATK and Soldier skills from using them.
"Powerhouse of Punishment"
Class Tree: Lancer → High Lancer → Dragoon
Advanced Class: Archdragoon> Executioner
A Lancer is a physical damage based class which specializes in the use of skill combos and putting enemies into "Break" state.
Skills include Paralysis, Defense break, Attack buffs, Defense Debuffs, Critical Strike Buffs, AOE
Lancers specialize in Lances and Scythes as they receive bonuses to ATK and Lancer skills from using them.
"Master of Magical Assault"
Class Tree: Mage → Sorcerer → High Sorcerer
Advanced Class: Wizard> Arcana Lord
Mage is a magical damage based class which specialize in dealing high single target and AoE magical attacks.
Skills include high damage single target skills, AOE, MDEF debuffs, and MATK buffs.
Mages specialize in Staffs and Charms as they receive bonuses to MATK and Mage skills from using them.
Class Tree: Archer → Hunter → Ranger
Advanced Class: Marksman> Sniper
Archer is a hybrid of damage dealing class and party support.
Skills include Poison, MATK/ATK skills, AOE, MDEF Buffs, Heals, and enemy Buff removals.
Archers specialize in Bows and Guns, as it enhances both ATK/MATK.
"Healing Hand of Life"
Class Tree: Cleric → Priest → Bishop
Advanced Class: Oracle> Cardinal
Clerics are an essential part of any guild/questing team.
Skills include healing, cleansing debuffs, and applying defense bonuses to other players.
Clerics specialize in Books and Relics, receiving bonuses in MATK and Cleric skills when equipped.
Clerics have no class that they are weak against, however in the purpose of Guild Battles, are generally the first to be targeted.