Knights: not good monster to hunt alone, but if you want to solo this, you should use earth-enchanted weapons like Cranial Basher/Mystic Blade/Heroic Axe rather than non-enchanted weapons. It's better to have a Druid or Sorcerer as shooter, using Terra Strike.
Paladins: with a blocker, shoot Earth Arrows; if you are going to solo them, use Assassin Stars and earth runes.
Sorcerers: can use Earth strike to kill these elementals. Not recommended to hunt these creatures on a sorcerer, as sorcerers lack earth attacks.