I recently played a necro about the same time as Acitavian and people kept summoning and killing his zombies to get mine! rather amusing. But when this came up on officials I posted there and still maintain that if people can summon/kill your zombies it wrecks a whole lot of real time in your game play. So you can either make them no summon - OR make necros like they used to be with no timer for raising. What are the advantages you ask? Glad you asked:

1. necro players can be rolling with a good full army within 5-6 minutes of logging in.
2. the strategic and tactical value of summoning away a necro's army still remains. It is a way to put a powerful necro out of action for right before you raid or counterraid.
3. It makes it viable to play necros if you have only forty five minutes or an hour to play

Thanks for listening and always like to hear feedback