Rathma's Vigor | D4 Necromancer Key Passive

Rathma's Vigor is a Necromancer Key Passive with the following effect (simplified):
Increase your Maximum Life by 10%. After being Healthy for 15s, your next Blood Skill Overpowers.

Once you select Rathma's Vigor as your Key Passive, you can't select any other Necromancer Key Passive. They're considered to be very important parts of your build, so it merits quite a bit of possible discussion.

How best to use Rathma's Vigor

Basically this segment will be giving you a rundown on the basics on the "WHEN, HOW, and WHY" of the Rathma's Vigor Key Passive.

Questions we would answer here would be like:
How to use Rathma's Vigor, as a baseline.
Why you would choose Rathma's Vigor over other Key Passives.
When would you consider Rathma's Vigor? As a build-around? An "augmentation"?

Rathma's Vigor Core Synergies

TBA: When choosing Rathma's Vigor, are there "absolute godtier" level synergies you essentially NEED to take?

Related Links & Other Information

Still got a lot to do, a lot of data to track, and how best to present it! Post-launch will clarify alot of this for us!

In the meantime, Related Links:

• If you're here, you're probably looking for some info on the Necromancer Class.
• Related Skill Tree Nodes: Rathma's Vigor
• Summary of all D4 Build and Character Customization Systems.