in h5, the only useful thing for armageddon seems to be hit-and-run tactics.You got to admit though it's an end game combo...
ideally using obsidian gargs, which take minimal damage from it.
I'm thinking that it must do some kind of secondary damage, or fire elementals, gargs, etc wouldn't be hurt by it at all.
if that's true, it might be an easy fix of the spells.xdb file.
still wouldn't help warlocks, but at least it would make a bit more sense.