I think one key way we may be mis-classifying Astral Slide is that the deck exists without it. "The astral slide deck" can just be the same blink deck, but with an astral slide in it. The Burning Vengeance deck is just a deck with flashback spells without burning vengeance, but can still be a deck (maybe worse). Astral slide is simply a blink enabler; the blink deck wouldn't miss it more than say, Galepowder mage, unless it would in fact be more overall powerful. Since the blink deck already exists, it just one tool in the deck. You don't not have a blink deck because you are missing one of the enablers. You don't not have a BUG graveyard deck just because you are missing the Sidisi, but she would have made it much more powerful. We just call it a new deck because it uses a unique avenue.
Thats a fair point, and one I can relate to. I run this card in the penny cube
Originally, I was kind of on the fence about it because I thought of it as a build around card, which it is in pauper, but it really isn't in cube. Build arounds don't fit into existing decks: they force decks to be built around them, which is why they are so problematic in cube where only 1-2 copies exist, and where they may never show up over the course of a game.
Tortured existence doesn't really require any support, as its just a variant of raise dead effect, which is quite a powerful effect in itself in singleton based formats. Any grindy black deck is on the lookout for these types of effects, and the threshold for playability is remarkably low: are you a slower deck playing creatures? This is like
recurring nightmare in powered cubes, which very quickly stops being a build around, because all you need to do is run it alongside any of the other million ETB creatures you were going to run anyways. Their is no actual building around that occurs.
This is different from, say, birthing pod. While its true that ETB creatures are fairly common, it does require you to draft around the concept of building a pod chain, which is kind of a bummer if you don't ever draw pod. This is something that even was noted when pod was legal in modern, that the deck played completely different in games where you drew pod vs. games where you don't draw pod, and which is reflected in the aggressive singleton breaking it receives in cube to even work.
Where does astral slide fall on that metric? I would say way past the point represented by pod, which is kind of reflected in all of the support we are talking about to add for it (singleton breaks, narrow tutors to get it, warping the entire way we work the basic land box, possible custom versions of the card). Even birthing pod doesn't require that level of support to function (and for the record I don't like pod).
The problem with astral slide is that its a combo card; it doesn't naturally fit into the blink deck
unless you draft cyclers to support it. And your reward for assembling your combo of slide, target, and cycler isn't that great (or consistent in execution): very close to the same thing that momentary blink can do consistently for far less mana and trouble.
Another comparison (and excellent example of the merits of flexible design that still provides draft direction) is
Galepowder mage, which doesn't actually need any specialized drafting or building to function: its perfectly fine incidentally blinking whatever ETB creatures you find or removing blockers so your ground force can hit--interactions almost as common to cube as the basic lands counterspell is cast off of. Galepowder tends to get miss-evaluated as a "blink" card for the "blink deck" when you really should be running it in any deck that can support a four drop. A reasonably sized evasive body that can remove blockers is game winning amazing, and the ability to value blink is just gravy.
And this is kind of that healthy spot that tortured existence or recurring nightmare inhabit (I can't believe I'm saying something positive about nightmare) where you might take the card down a certain drafting direction, but its independently strong enough to stand on its own, and doesn't ask the drafter to warp their draft around them,
unless they wish to. Its hard for me to see Astral slide inhabiting that space, without
a lot of invasive support, and even than I'm skeptical if the payoff is worth the trouble. At the end of the day its just an exotic blink effect.
Sorry if it seems like I'm dog piling btw, just an interesting topic.
