Also, I imagine his elementals are edged and he doesn't just summon small ones, every elemental he summons he puts his maximum mana into with the Djinn out, and uses slow to recover and bind fast. Any conjurer that does that will be dumping that sort of damage, I've had about a dozen with the same results. They're nice and don't die as fast as people say.
90% of the time, hes going to have a transplendant. You won't always have something to tank it. Fighting their archon is not viable like 90% of the time. In cabal wars, you don't always have the option to just "not fight" Sometimes yes, but not always.
They smash peoples faces in, obliterates on unprotected foes demolishes through just protection usually. Most classes can't handle that and the elemental.