RE: Nerf to unplayability all units with Destroy Target
I don't like the OP's "adjust cost" philosophy either, which I expressed in a top-level comment. Far better to rework them to normally playable levels. (I also really hate the idea of "safety valves" in a meta with counters like this, which is commonly used in MTG and other similar games.)
The comment about "Other pieces in army" is an F3 meme. It is very oversimplified. But it's not that far off IMO. It's because the way Antimage is bullied off from affecting Ranger is with low-to-mid-cost minions, which is not really something you can say about Ranger. Of course you could say the Antimage player should just run a Rangerlike of their own, but, y'know. Trading off is harder than it seems, in order to actually get it you have to run things that are like +3 points more expensive than the unit you want to trade with, which is obviously really bad. (Not to mention defensive units that can deny even this, like Guardian/Minotaur/Vampire - but it's a separate problem.)
I guess I didn't mention another aspect of a Destroy meta that makes it an actual problem compared to other metas, IMO: it is almost a complete removal of minion structures. Classic Chess has the tension of pawn structures keeping certain areas of the board "locked up". In CEO, we could have had 'axeman structures', 'spearman structures', etc. but with the existence of Ranger-likes, that entire element is gone. I think that's the more important part to me, since it's not necessarily bad for a single unit to be commonly used in a meta IMO (if the unit is popular and deep, even if it's OP but you can only use one).
But I almost completely agree with your take otherwise. It was particularly because your original post mentioned Lilith at the end as a "more defensive" thing, when the OP mentioned Lilith being a problem magic unit as well. (btw, I'm not sure Lich armies are necessarily forced to be OP against pure melee armies, they have to deal with morale too. Yeah, Dryad and Gemini cheese this and are the main reason they are OP, but assuming these don't exist, an infinite unit generator that costs morale and doesn't have 'cooldown' could still be a fair game versus normal melee armies.)
Also, I thought I only mentioned 2-for-1 trade in the context of an Axeman if all you had were expensive minions, not with Lilith. Sorry if I mentioned it in a Lilith trade context, there's usually no good ways to 2-for-1 against a Lilith.
I do agree that ranger does lock out lots of minion structures, but at the same time I do worry that lots of minions structures without a ranger would be completely inpenetrable without tanking your morale in some way. Like you mentioned you don't know whether 1 cost axe is op because of destroy metas, but I do think there's a high chance that it would in fact be op, such as this sort of thing:
(Pretend the wisps are some expensive pieces like vamp+++ or something cuz i dont have these pieces)
Itd be pretty difficult to breach this with no ranged/magic and a line of samurai even if you manage to trade some of the samurai 2 for 1. And if you're running even more expensive minions then you heavily tank your morale even with a 2 for 1 (samurai+0 isn't even THAT expensive) . I kinda worry that having some sort of range/magic is essential anyways for armies due to setups like this, so taking out range destroy would just make everyone switch to the other options like thunder+EE or something
It's hard to say for sure since some of the counters to two axeman like that cause terrible design issues themselves (Behemoth). Also like you mentioned it would be possible to rework destroy effects to give more compensation to the one whose pieces are getting destroyed for free, but in the particular Axeman case, Freeze/Petrify/Wind/Siren can serve as solutions to this with counterplay.