says light monster, not healer monster. you can limit yourself to light healers only but...
As for maintaining full hp all the time, she DOES have a shortish cd heal (consider you will likely have 2 cuz teammate), not sure how easy it will be to skillup. Also, as someone who has made use of zeus from time to time... full hp requirement is not much of a drawback for dungeons where virtually everything is "kill before I 1shot you", and those seem to be more and more common sadly.