Or Magebane, for that matter. A couple of hit at +100 unresistable fatigue makes it rather likely the victim will never return to haunt you, unless he's immortal in his own dominion.
In this case, 'tho, if somebody's surrounded by a horde of undead, and there are skellispammers (which seems likely to me -- you can't reanimate when under siege, but you can cast rituals to summon more), the likelihood of getting to the main target before time runs out might be pretty low. You'd at least want a damage shield like Charcoal Disk of Death (or better, Aegis...
), flight if storms isn't an issue.
TC does have air mages, if memory serves -- at least for the first two eras, haven't tried late -- so Seeking Arrow might be an option if you can get an A3. Mind Hunt might also be available, but dodgy considering that an undead-happy nation might have spectres, and spectres can have astral magic -- need to be careful about this if the feeblemind is a problem.