I would get defend/ and try to toggle and control timing usage of that skill,
Well it really depend on your hero, because if your hero is a mage then you get more damage blocked, according percent of damage you take. This skill is mostly effective in late game, or you could level just one level of this skill at the skill after your farm skill
Also another good defensive skill is slow ward, best if ranged player because that would allow you to give extra attacks in the late games