The solo, non-elite, Warden quests which have you kill empowered rare mobs to me seem exceedingly difficult for something advertised as a solo quest. Unless you are a powerful solo class, like Hunter, they just hurt too much. Do about 20% of your health in 1 auto attack.
If they are intended to be soloable at fresh 110 gear I think their auto attack damage needs to be nerfed considerably, and possibly their actual abilities buffed.