On another note... an "undeath" necromancer? If I might make a suggestion, perhaps rename that spec to Corpseology. As well, I think that it would be best for that spec to just keep with undead creations rather than powerful entities like liches and crypt lords... Those guys aren't really minions. They're powerful creatures in their own right.
As well, would corpses be mostly a cooldown thing or a frequent use, because I don't think that if they're supposed to be used often it will be a viable mechanic during a good number of raid bosses. There's also the fact that you'd have to gather corpses. They got rid of Soul Shards for a reason... I dunno if a mechanic like that would float in the game as it is being developed now.