Primary

 Intelligence
 Strength
 Agility

Damage

 Physical Damage
 Elemental Damage
 Melee Damage
 Ranged Damage
 Fire Damage
 Ice Damage
 Light Damage
 Critical Damage
 Armor Penetration

Defensive

 Health
 Mana
 Armor
 Resistance
 Dodge
 Tenacity
 Life Steal
 Mana Steal
 Spell Vamp

Miscellaneous

 Move Speed
 Attack Speed
 Projectile Speed
 Cast Rate
 Jump Force
 Range
 Melee Range

Projectile Speed

Projectile Speed determines how fast a caster's missiles will travel. Higher Projectile Speed allows for more accuracy, as it results in missiles closing the distance between the caster and the target faster. Projectile Speed is important for Projectile Abilities like  Fireball,  Ice Shard,  Holy Bolt,  Shadow Bolt, and  Lure.