Sorry but "Blood ritual" is the worst talent you can take on 4. The only viable option for EVERY build is "Big Voodoo". Nazeboo is a late game hero. He needs his stacks and high health. You have no escape (No! W is not an escape. It can help but not against most mobile heroes.) and when you take "Blood ritual" your just an easy gank hero. There are way too many heroes. that can burst you in seconds.
Late game "Big Voodoo" makes you a "tank" in mid/late game. Esp. with ice block. They can`t focus you fast down and if they ignore you they will receive heavy damage. That`s his true power. An