[Verjigorm]

Giants do care about it unless they have Regeneration. Since the spell goes off before battle, just like FFtS and FFA, the damage will remain on the unit when it enters battle, so even though it won't kill a giant, it significantly increases the probability of their death in combat by essentially cutting their HP in half before battle. Very powerful defensive, but still good offensive (outside dominion) too. With near complete control over my own dominion I still see up to 200 injuries and 70 deaths each turn which can be a considerable expense for any nation.

Of course, the spell is obviously a diplomatic nightmare... Sort of like nuking a childrens' hospital.... so I would generally save my gems for something like Fata Morgana which will give you an income/resource/supply boost, lower unrest, free phantasmal PD and is not injurious to others so diplomatically better and on top of all that costs 30 fewer gems than WoG which has a greater chance of causing everyone to gang tackle you or dispel it since it kills mages with annoying frequency. I think, WoG, like Burden of Time or Astral Corruption is likely to cause others to hate you, so you should only use it if you know you have the strength to counter what comes at you afterward as it is essentially the commission of an act of war against all of your opponents.