A new race – the Order of Knights of Elrath.

To make the difference more obvious, why not replace, for example, the third creature type with healers (spell: regeneration; ranged attacker), then a witch doctor (remove curse, regeneration, melee attack, poison), and a light inheritor (crystal of secrets, regeneration, ranged attacker). Among the larger creatures, you could add heavy catapults (they don't retaliate against enemies, but they can attack if an enemy is nearby). A steppe hunter (definitely a camel rider) attacks everyone around him, with an endless counterattack.