Dryad

Ally unit 

Great support unit. Most players tend to avoid her. She has a lot of health and if properly handled will last until the last round. If you use once or twice the Warlord blessing ability on her, the Dryad will be a decent attacker as well. One of the few ranged units that can be used in the first row without worrying she will die too fast

Combos 

Always use the Dryad in combination with Shaman, Druid or Cleric. The healing abilities of the Priest or the Paladin will be wasted on her.

Enemy unit 

You can easily disable the Dryad with the Warlock's curse and than forget about her until the end of the combat. All poison attacks (Viper, Hydra or Black Widow) block her enhanced healing ability.