I have two things i want to state.
1.There is a bug with heartless(a mage skill in the skill tree), the mana health doesn't protect against drowning damage
2.Compared to mage and warrior, ranger class doesn't have much sustain(life leech). Warrior class has life leech and mage class regenerates mana quick, has a huge barrier, and uses mana as health. Ranger doesn't have any of them so i suggest making a skill for rangers, to regenerate 0.5-1% percent of ranger's health every time his/her attack crits(because ranger attacks quick, 0.5% is enough i think).
I know that ranger also have the dodging ability but its just not enough, because other class can have the dodging ability in addition to another way for getting health.