Fire and Brimstone bug or intented?

Classes Warlock
1

I just notice that Fire and Brimstone does not generate additional soul shards, is this intended or just a bug ?

2

Pretty sure this is just some extra cleave damage from your incinerate, based on how it reads. Could be wrong though. If it were a bug and it was fixed, FnB combined with Diabolic Embers would be nuts.

3

I believe this is intended.

4

So is Fire/Brimstone preferred over Rain of Fire dmg increase?

5

I use both on my mythic+ build.