For year, I haven't seen a single build that make the use of the Blood Hatred skill.
I tried it myself and it suck. It serves no purpose.
Weapon Attack skills in Median have 3 main styles:
+Aoe: to kill Aoe. Median monster density is massive, so they are usually primary attacks
+Single: to kill bosses, stationary target, often strong with absurb damage
+Buff: usually single hit that buff the character
What style is Blood Hatred??
+It is clearly not Aoe skill, so you can't use it as main attack
+Single: want to kill boss with this? you empty all of your mana after a few hit. So you can't.
+Buff: you must hit 3-5 hit to activate the buff, on a single monster, you lose a lot of time and effectiveness by doing this. So you can't.
I have tried many thing to revive this skill but was in vain.
It is so underwhelming now, I suggest some changes (but not all of them should be used):
1/Remove mana cost, the skill cost life already
2/Give it a small proc chance that proc a Fire/Light/Cold blast for a small radius, this suit well with the Element pierce nature of the skill
3/Make the buff become effective with just one hit