Has everybody else noticed this or is it just me? I havent seen regeneration listed as an ability of any of the new devils. Havent devils ALWAYS had regeneration?
No, devils don't always have regeneration. Imps, Kytons, Cornugons, Gelugons and Pit Fiends have regeneration (under 3.0 at least...). It's not a baatezu-ability per se.
That was the retriever -- it was a construct with regeneration.
(Regeneration means most damage is taken as subdual damage; constructs are immune to subdual damage; ergo, pre-errata retrievers are immune to all damage that doesn't come from blessed or holy weapons. That would include fireballs, magic missiles, smackdown characters that forgot the holy weapons... A bit much.)