Not if you don't know about the extreme harshness and (arguable) bugginess of the routing rules in this spell's battles! Of course I'd do that stuff NOW, but, see, that unit I just lost has been with me for a year. This isn't Starcraft or something, where you lose your awesome unit that you love and then start a new game twenty minutes later and build a new awesome unit! People should be expected to roll with the punches most of the time, yes, but not ALL the time--not when they're as nasty and cheap as this!
A dude in the thread linked below (which, again, covers most of this in great detail) claims that even living (as opposed to undead) immortals can be permanently killed by this spell! THAT I would not expect--not as a new player, not even as a person who's been playing for years.
So, this problem warrants a pre-game warning.
(Part of the reason why I'm keen on this "warning" idea is that, now that I know how crazily harsh Vengeance of the Dead can be, I'm going to start casting it more against my own enemies! And if I don't warn them first, I'll feel like a jerk.)