Castle Ardenvale is definitely the weakest of the cycle -- paying five mana to create a 1/1 is terrible value -- but even then, the risk is so low that I'd definitely give it a shot in any Mono White deck and would seriously consider it in any 2C deck that runs Skullclamp
You can tell that Wizards was scared of putting improvise on a scalable effect because this is literally the only one with X in the cost, but that ability to kill essentially anything is what draws me in
(It also refers to Intuition, a concept thats far more red/green than it is blue, so the cards also problematic in its flavor.) Those Pesky Rules, Though Gifts Ungiven is the second take on Intuition, and its much more successfulthough it still has a big asterisk
But if time is the limited resource that is spent flipping sieges, players will probably prefer a more meaningful threat to reward them for that effort and hopefully end the game sooner
I will say that this Sylveon ex artwork goes hard, and is much better than the artwork we got even in Evolving Skies, only lending to its stellar value