"On the clean skull of a man or humanoid, the sorcerer places a ward that lasts 1 turn or until touched by another living creature. If the skull is touched by someone other than the caster, or at the end of the spell’s duration in any case, it explodes with waves of negative energy from the Black Gulf."

JRR wrote:

Wow, I read that at least a dozen times and missed the duration.  Thanks. 

Since the damage is negative energy, I assume it won't damage undead?  Could a necromancer send in a horde of skeletons to attack his enemies and then toss a grenade in the midst without harming his minions?

I don't believe it is explicitly stated in the rules, because we don't get into the Positive and Negative Material Planes in AS&SH, but I would probably allow what you are suggesting. It sounds like a great tactical decision! 

 

Handy Haversack wrote:

Could the necromancer cast it on the skulls of his skeleton minions? Sounds like a big yes--as long as they're clean!

And, frankly, if you're tramping about with dirty skeleton minions, you don't deserve the title necromancer. Stay out of Scythium, deadbeat! Keep your ugly Pictish goldbricking ass out of my dread and fell beach community!

but...how does one polish a zombie?

I can envisage a billboard in downtown Kromarium:

Zor'Thax's Zombie Polish!
....for the discerning Necromancer!