The Gloom rune of the demon hunter's Shadow Power skill is as follows:
Is the 35% reduction in incoming damage in addition to the 15% damage done as Life, or instead of it?
I sometimes have difficulty determining this for other runes. For example, the witch doctor's Rabid Dogs rune indicates "Your Zombie Dogs gain an infectious bite..." and "Swallow your Soul" indicates "Gain X mana...". In these cases, the effect specifically indicates that it is in addition ("gain") to the base skill.