Combustion | D4 Sorcerer Key Passive

Combustion is a Sorcerer Key Passive with the following effect (simplified):
Your Burning effects deal 2% increased damage per unique source of Burning you have applied to the enemy. If the enemy is Burning from 3 or more sources, this bonus is doubled.

Once you select Combustion as your Key Passive, you can't select any other Sorcerer 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 Combustion

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

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

Combustion Core Synergies

TBA: When choosing Combustion, 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 Sorcerer Class.
• Related Skill Tree Nodes: Combustion
• Summary of all D4 Build and Character Customization Systems.