If you backup level there are a whole bunch of angel types I had never known existed. Ofcourse I hven't played the gme since the 90's I just read the novels..and I have never come cross any of these types of angels in any one of them.
From that write up, it looks like a Seraph is atleast a double powered Solar...!
Anyone know where I can get info on the 4 Seraphim? Are they still canon under the new rules?
I don't think they were ever canon in the sense of being integrated into any particular setting or the general AD&D metasetting. That's a conversion of material from a 1980 Dragon magazine article, and I've never seen any reference to it outside of that source, though I'm hazy on some stuff prior to 2e. It's certainly not something referenced in 2e or 3e planar material as I'm aware of it.
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The closest thing I have ever seen to that in 3e sources is in Anger of Angels. A great book if you can find an e-copy somewhere, or at a bookstore. A truly wonderful source if you are adding angels into your existing campaigns in a grander sense than normal.