When Vraska, Golgari Queen was first spoiled, it generated some conversation in my Facebook group, as to whether or not her first ability represented Card Advantage, or as some suggested, Card Disadvantage.
The entire concept of Card Advantage is both nuanced, and not well understood. I’m no expert, but here’s my thoughts. Feel free to agree or politely tell me I’m full of shit. It’s all good 🙂
On it’s most superficial level, Card Advantage is simply spending one card to get two cards. A card like Divination is the cleanest example of something like this. You cast Divination (-1 card) and then you draw two cards (+2 cards), so your net gain is 1 card. This is also applicable to cards like Mind Rot in the opposite direction. You cast Mind Rot (-1 card), and your opponent discards two cards (-2 cards), so you’re seeing a net advantage over your opponent of 1 card.
Another aspect of this type of Card Advantage is spending one card to remove two of your opponent’s permanents, because the “Card” in Card Advantage isn’t just referring to the cards in your Hand. This is why Creature Auras have always been problematic, because they carry with them a significant, inherent risk of Card Disadvantage.
There’s also the concept of “Virtual” Card Advantage. One example of this is getting more than a card’s worth of value from a single card. For example, a card like Call the Cavalry creates two 2/2 Knights. Well a 2/2 creature is “worth” about a card. Which is to say, if you had a single card that created a single 2/2 creature (“Bear” is slang for this, btw, for those of you new to the game), you might play that. So Call of the Cavalry is Virtual Card Advantage, because its effect is more valuable than the baseline of one card.
Gradations on this are also a factor. If you’re netting some percentage of a card’s worth of value, then it’s a form of Card Advantage. For example, Attended Knight is a great example of this. It’s a 2/2 that creates a 1/1 when it ETBs. Well, a 1/1 creature is not typically worth an entire card by itself, but adding another body to the board has some value, so it’s worth some percentage of a card. Scry and Surveil are also in this category, of being worth some portion of a card. Neither is quite as good as just drawing another card, but they’re frequently close in value – especially later in the game – because they’re helping to net you a relevant spell, instead of an extra Land or irrelevant spell.
Exchanging resources for cards is another form of Virtual Card Advantage. This is the concept of replacing an unnecessary, or unneeded resource to draw another card. This is what makes Cycling such an excellent workhorse of a mechanic. It’s why the Guild Lockets are actually playable, even if they’re not particularly good. This is also part of where Vraska can generate Card Advantage, as you can trade away a Land you don’t need for life and card draw.
Lastly, there’s an axiom in Magic that the person who casts the most spells is generally going to win. There’s some truth to that and it shows up a couple of different ways.
One way is Aggro strategies. If you’re accelerating the pace of the game, you’re reducing the number of turns, and therefore Draw steps your opponent has, thereby limiting the number of cards they have access to. You’re generating Virtual Card Advantage through speed, because your opponent is drawing fewer cards than you are.
Another, and again, this is relevant to Vraska, just digging deeper into your Library generates card advantage, even if you’re not netting an actual card in the process.
This is why cards like Ponder and Preordain are so powerful. Enough so that they’re both banned in Modern. You’re still exchanging one card for one card (card parity), but you’re just drawing more cards, so you have more access to what’s in your library, and more access to the spells you’ll need to win the game. Running 4 Opts, or 4 Cycling Lands is almost like running a 56 card deck. On the surface, these are both Card Parity (one for one), but they both generate Virtual Advantage by giving you access to more cards, and the increased probability of drawing a relevant spell.
One last note, some of what I say above applies to the concepts of card selection or filtering, and deck manipulation, but I don’t think that they’re completely separate in how they work and effect the game.
Have fun, Play on, and Be kind to one another.