Yeah I think it's pretty clear that the thought process was "People are asking for Force of Will in Modern but we don't want to print Force of Will in Modern, so how can we make a fixed version?" followed by "It would be cool if we made a cycle of pitch cards to go with this one." You only have to look at the names to see that the blue one led the way.
If you set X=20 or something ridiculous like that it might be worthwhile, but only because it makes progress towards a mill victory. If you only want to consider the value of exiling the cards (like if you imagined that there was no possibility of removing their whole deck for whatever reason), I'm not sure any value of X is better than any other value.
Let's say in my example X =20 and your opponent has 40 cards left in their deck. They have one wincon in the deck (again, for simplicity sake).
I think the thing with this example is that there are better cards if your opponent truly has one win condition in their deck. One mana to have a 50/50 chance of winning on the spot seems great, but for two mana you could play Seek and have a 100% chance. That along with Sadistic Sacrament (which hits their backups too, if they have them) are pretty fringe cards because they're very narrow as it is, but they do destroy a deck that doesn't have a way to win without a crucial one-of. So if we're considering random mill, I think we have to consider what it does or doesn't do against "normal" decks that have a bunch of threats, because if you're targeting the decks that fall apart without one card you probably wouldn't choose to play Super Tomb Scour anyway.
@protoaddict 6/4 is the ultimate power/toughness anyway so you still come out ahead.
No, that's a relevant point though. I think that infect in Vintage has been a very fast goldfish that's very easy to poke holes in, and this card makes the goldfish faster and/or easier to assemble but no less hole-pokeable.
Sorcery - Uncommon
Until end of turn, target creature you control becomes a Wurm with base power and toughness 6/4.
They should have sent a poet. I don't know if this is going to make it in vintage, probably not, but I do know that a) this callback is ideal, b) I'm going to make a bad infect deck with it, and c) I really hope the English name is Crawify.
@chubbyrain I think it's easy to miss how good a draw engine she is because the Leovold ability is such an attention-grabber. But once you posted the Dig comparison here it clicked for me. It's a little less good than that and has a different play pattern obviously, but Impulse with rebound is really strong at 1UU.
I've been using this as a four-of in its own shell with rituals, shops, Aetherflux Reservoir, tutors, some other artifact stuff, etc. I have yet to lose a game after resolving a Citadel. This card is absurd. Bargain doesn't even feel like the right point of comparison... this is like if Mind's Desire didn't even need a storm count and let you play as many cards as you want. It's an upgrade over Bargain the way Time Walk is an upgrade over Explore.