The Bruiser unit is fire-aspected, and represents strength. It does double damage to Archer units.
The Mage unit is water-aspected, and represents intelligence. It does double damage to Bruiser units.
The Archer unit is earth-aspected, and represents dexterity. It does double damage to Paladin units.
The Paladin unit is lightning-aspected, and represents charisma. It does double damage to Mage units.
The mercenary unit is unaspected, and represents raw power. It has no strengths or weaknesses to other units.