The Undervault is very good bashing, for Mag/Glom and for Seren/Celest. Kephera are usually in groups and don't move enough which can make them difficult, but they are very good (read: much better than illithoids) for gold, and the experience isn't horrible. It's not as good as linked astral, but it is much more accessible if you don't have a cubix or can't survive mass-linking. Illithoids are not as great (but not horrible) for gold, but better for experience and essence since every one has a worm. I don't think they are as numerous as the kephera, but definitely nothing to turn your nose up at. I hunt them more than astral.