Let's see if this plan for 5 race and 6 class works. Remember this is based on popular MMO race and class. Although Vampires are not as popular in MMOs, in our Magic style MMO, they are a major race because I needed a black race. Fortunately, they also fit great with the other theme of this set--gaining and giving control.
Primary color in uppercase, secondary in lowercase, tertiary after dash.
CLASSES (3 fighter class, 3 mage class)
Note: Dual-classes are for flavor only, such as card names, major ruling body, or possible legendary figures.
Humans are white, then blue. Their classes are Soldier, Cleric, Wizard, and Rogue. Dual-class is the Paladin, which is a Cleric Soldier.
Gnomes are blue, then green. Their classes are Wizard, Rogue, Druid, and Warrior. Dual-class is the Illusionist, which is Wizard Rogue.
Vampires are black, then red. Their classes are Rogue, Cleric, Wizard, and Warrior. Dual-class is the Bloodmage, which is Rogue Cleric.
Dwarves are red, then white. Their classes are Warrior, Wizard, Cleric, and Soldier. Dual-class is the Battlemage, which is Warrior Wizard.
Elves are green, then black. Their classes are Druid, Warrior, Rogue, and Cleric. Dual class is the Ranger, which is Druid Warrior.
If each class belongs to two or more colors, let's distinguish them even further as such. e.g.
Blue wizard = Cryomancer (ice mage)
Red wizard = Pyromancer (fire mage)
White cleric = Buffer (protection, bonus)
Black cleric = Debuffer (sickness, malus)
Black rogue = Stealth
Blue rogue = Trickery
Red warrior = Rage
Green warrior = Inner power
Now how about racial qualities?
Human: white-blue represents mercantilism (transactions, playing into the control theme)
Gnome: blue-green represents philosophy (exchange of ideas)
Vampire: black-red represents treachery (stealing creatures, another control theme)
Dwarf: red-white represents industry (mass production; give away freebies?)
Elf: green-black represents burial rites (stealing from the grave, graveyard manipulation)
One may divide the classes even further, since each class for each of its two colors also belongs to two races. This means there are four flavors of rogues, wizards, warriors, and clerics, and two flavors of druids and soldiers. As such the descriptions for each race should be expanded upon at this time.
Humans live by the sea and prefer peace over war. A huge portion of their economy comes from trade across the sea. Thus seafaring is an important part of their lives.
Gnomes live underground in snowy lands. Winter is their favorite season, and they like to cause mischief for passersby.
Vampires prefer dark areas and operate mainly at night. They convert their victims to their side through various means.
Dwarves operate mines and machinery. Their expertise in machine weapons gives them an advantage in warfare.
Elves revere the lands and don't like outsiders intruding on their lands.
So by their racial differences, we can split the classes accordingly. For example
Human clerics heal and protect.
Dwarf clerics buff and strengthen.
Vampire clerics weaken and drain.
Elf clerics debuff and taint.
Human wizard specialize in water magic.
Gnome wizard specialize in ice magic.
Vampire wizards specialize in causing fear and chaos.
Dwarf wizards specialize in explosions and destruction.
Human rogues are pirates since robbing seafaring merchants is very profitable.
Gnome rogues play tricks on others.
Vampire rogues are the most stealthy.
Elf rogues are excellent trackers and hunters.
Gnome warrior favor speed
Vampire warrior favor dominance
Dwarf warrior favor aggression
Elf warrior favor strength
Human Soldier are defensive
Dwarf Soldier are offensive
Gnome druid know secrets of the mental realm
Elf druid know secrets of the physical realm
Based on the above descriptions, we can assign the abilities respective to each race and class. e.g. Human Rogue (pirate) can steal things when they hit an opponent. Human Wizard (water mage) may cause floods and turn lands into islands. and so on.