The text of this card reads:
"After each effect that destroys Towns/Cities/Dahan in target land, 1 damage per Town/City/Dahan destroyed.
Let's say I am doing five damage in a land with two cities and a man in it. If I read this card and execute the instructions, I could assign three damage to one city and two damage to the other one, then Vengeance gives me a damage, which I use to put a third damage on the second city, and then I'll get another damage I can use to kill the man. If I just read the card and execute its instructions, this is what should happen.
But I go online and this is not what happens, I don't get that last damage so the man remains. I go to report a bug but I'm responsible so I look up the FAQs about the card and sure enough, this behavior is intended. Vengeance doesn't trigger off itself.
My first thought is, the FAQ shows that this is intended behavior, so why doesn't the card text reflect that? It would be so easy to just say "After each OTHER effect that destroys..." and now bam, the card says what the card should do while adding only a single word to the text. At the very least, if the card has to be this way, I would argue that it should be errata-ed to reflect what the card actually does. I had been playing it incorrectly IRL the few times it came up because the card was so clear on what it did (but maybe also because this was only clarified in the Jagged Earth rulebook). Honestly, if this is how things are going to be and the card isn't errata-ed, I'm just going to take it out of my IRL game. I even read this FAQ and then tried to use a Powerstormed Vengeance of the Dead on a land and that didn't even work how I expected -- I can handle complexity in games but this is ridiculous, the ruling here and how it applies to Vengeance of the Dead for some arcane reason just makes the card so complex that every time I execute the card text online (which I assume is the "correct" way to execute the card) I am unpleasantly surprised that I get less damage than what I thought I would. It will usually result in me undoing back to when I took Vengeance and picking another card, which seems like Vengeance is now a complete failure of a card on all fronts. Not good.
I would argue that the ruling to make Vengeance work this way is something that should be reverted. The only reason I could possibly think of is if you could somehow use Vengeance and Bringer's special rule to somehow destroy a town an infinite number of times, giving you infinite fear and just winning you the game, but after a lot of searching, I don't see a case where this is possible that this ruling prevents (to be fair, if there is one that I haven't found, I could see an argument for keeping the ruling, but then I would consider just adding a clause in an FAQ somewhere that fixes all infinite fear combos by saying something like "you can't use Vengeance to kill the same town/city multiple times in one turn" instead of this ruling). I can dream up ways to use Bringer to get infinite fear without even using Vengeance! The best this ruling does is turn "kill X towns" into "kill all towns in that land and maybe some adjacent lands" which honestly doesn't seem like too much of an effect given what you have to go through to set it up. It's not like Vengance is a powerful card anyways, it's so situational that I can never justify taking it unless it's going to be immediately useful, and that situation is so narrow and the effect is so weak most of the time that this card does hardly anything, not nearly enough to justify its huge energy cost and being a major power. Seems only fitting to have the potential of this card to be niiiice and high so that you might ever take it before the heat death of the universe. Killing all towns in a land is something that Jungle Hungers just does by itself for the same energy cost and while I will sing the praises of that card all day, nobody is calling for nerfs because killing all towns is "just too powerful" or something.
So yeah, this ruling on Vengeance is one that is not written on the card though it easily could be; results in either the card being "misplayed" if it's IRL and nobody is there to police people to play it "correctly"; or for some rules police or the online client to give you less damage than what you were expecting in a way that is not only too confusing for people like myself to even understand, but in a way that leads to an AWFUL player experience; and finally I have searched for quite some time to find a reason why the ruling needs to be this way and I just can't find anything at all that makes any sense to me.
Vengeance, the way it works now, is very not good and it needs to be changed. The easiest way to fix the card is adding a single word to the text, but my recommended way of fixing the card would be to take out that ruling and just let the card do what it says it does now. I feel strongly enough about this that if nothing changes on the card I'm just going to take it out of my IRL game and just never pick it when I see it online and lament the fact that I only get three Majors to choose from sometimes.