Zariel is a tough one because 5e is the first edition when she has made a real appearance. She was referenced in 3e, but she had been replaced by Bel, who is most definitely a warrior type. Bell has historically been on of the weaker Lords (see my
post #15) and because he replaced Zariel we might assume she has a similar CR. So that could make her one of the weaker Lords. Also, historically the Lords generally get stronger the deeper into Hell you go. That was strictly true in the Fiendish Codex, but less so in the Book of Vile Darkness.
If we extrapolate the above information into 5e, then we might expect Bel and Zariel to have similar CRs, and they do "officially" (CR 25 & CR 26 respectively). If Bel is near the bottom of the Lord rankings, which he always has been, that suggest the rest of the Nine are at or above Zariel's CR.
However, I think my ranks may need some adjustment. I am in general agreement with
@cbwjm that most of the Lords should have a similar CR. That would bring Zariel up on par with most of Nine. So I am thinking of raising most of them a bit. Something like this:
Layer of Hell (Lord) | Lord CR (5e) |
---|
1st (Bel / Zariel) | 25/26 |
2nd (Dispater) | 26 |
3rd (Mammon) | 26 |
4th (Belial & Fernia) | 26/26 |
5th (Levistus) | 26 |
6th (Glaysa) | 26 |
7th (Baalzebul) | 27 |
8th (Mephistopheles) | 28 |
9th (Asmodeus) | 30 |
What do you think?