What are you waiting for?
You ought to ask yourself this question often. Applying for your dream job? Asking out the girl or guy you like? What are you waiting for? It's a good question to ask yourself in a game of Magic as well. After all, nothing's going to happen if you just wait around.
Well, that's not entirely true. Something is going to happen. In life, Benjamin Franklin pretty much told us what it is, "In this world nothing can be said to be certain except death and taxes." In a game of Magic, the question is a little bit more complicated.
What is Inevitability?
So what are you waiting for? What's going to happen if the game drags on indefinitely? In most cases, one player or the other will have an advantage as the game goes long. If one player is virtually guaranteed to win the game if it goes long enough, we say that that player has inevitability.
When we discussed control decks, I made the statement, "You have inevitability if your deck is powerful enough that you'll win a very high portion of games that go long." In truth, the concept of inevitability is even more extreme than that. I might have a powerful deck with lots of card advantage, but if my late-game strategy does not utterly and unquestionably crush my opponent's, then I don't really have inevitability.
Consider this test: if you were to let both players draw 30 cards and spot them 100 free mana every turn for the rest of the game, who would win? You'd probably expect it to be the player with the more expensive and powerful cards, which sometimes it will be. But what about the player who has enough burn spells to kill you from 20 life? What if one player had cast Scout the Borders and will therefore run out of cards before the opponent?
Things begin to look strange when you consider the extreme long term, but these are important questions to ask. They all serve the larger question of "What are you waiting for?" I can have the patience of a saint if my waiting will eventually lead to a win. If I'm waiting around to die, on the other hand, I'll look for ways to speed up the game and end things before it gets to that point.
The question of which player has inevitability is important for both deck building and for your in-game decisions. If you have inevitability in a given matchup, you can focus on defending yourself and simply seek to survive. If your opponent has inevitability, you need to force the action and try to end the game.
Inevitability is a late-stage issue. Inevitability is concerned with a point in the game where tempo no longer matters. It's a point where both players have ample mana and ample time to spend it. More than that, you can think of it as a contest of a complete deck against a complete deck, instead of about whatever particular cards happened to have been drawn early in the game.
I first brought up inevitability in the context of power and card advantage, and it is most certainly related to those two things. However, it's also about ensuring that your late-game plan trumps your opponent's late-game plan. Your opponent must not be able to shut you down—by killing your creatures and Planeswalkers, for example—and must not be able to circumvent your defenses and kill you directly—as with a flurry of burn spells.
Control decks tend to play a small number of win conditions, but the ones they do play tend to be very reliable and very resilient. They're chosen in order to grant inevitability.
A single Pearl Lake Ancient will beat out an unlimited number of Hero's Downfalls, Murderous Cuts, and Crackling Dooms if it's given enough time to do so. If the win condition of your Blue-Black (UB) Control deck was Riverwheel Aerialists, then a single removal spell would be capable of shutting you down. Even if you played two, or four, or twenty creatures along the lines of Riverwheel Aerialists, it would still be within the realm of possibility that your opponent could kill all of your creatures and leave you floundering. Pearl Lake Ancient provides inevitability in a way that other cards cannot.
This time one year ago, White-Blue (WU) Control was a popular strategy. Traditional knowledge was that Elspeth, Sun's Champion was the "best" win condition. It had a huge immediate impact on the board, finished the game quickly, and was good in virtually every matchup. The problem was that against a deck with ways to answer Planeswalkers, it could come up that your two or three Elspeths could die, and you'd no longer have an easy way to win the game, no matter how much card advantage you accrued.
Control players began to turn to resilient win conditions—either Elixir of Immortality or Ætherling—to combat the problem. Elixir and Ætherling were much slower at impacting the game than Elspeth, and therefore they were cards that you never particularly wanted to draw early in the game. Nonetheless, the presence of a single copy of either card in your deck meant having inevitability. If you could survive indefinitely, you would win by recycling your graveyard (in the case of Elixir) or by attacking with an unkillable creature (in the case of Ætherling).
Stopping Your Opponent's Endgame
I've stated that a single copy of Elixir of Immortality or Ætherling provides inevitability, but this claim is rather silly because question of inevitability is related to how two decks match up against one another. Of course, it also matters what your opponent is up to. What if your opponent also has Ætherling? What if your opponent has something even more powerful? Perhaps something I'd never even thought of before?
If your goal is for the game to on indefinitely, you must have a plan for all eventualities. A good way to do that is with permission spells. Dissolve can stop your opponent's Ætherling. It can also stop your opponent's Crater's Claws for 20, or it can stop whatever spell your opponent might use to take your win condition away from you.
Dissolve is a hard counter—it can counter virtually any spell under virtually any circumstances. Something like Temur Charm is a permission spell, but it is not a hard counter. I like to include at least a couple of hard counters in any blue control deck that I build, because they're great for locking up the late game and contributing to inevitability. Sometimes their early-stage applications aren't great, but in the late stage, when you can save them for the small number of cards that might give you trouble, they're invaluable.
Another way to contribute to a deck's inevitability is to include lifegain. Experienced players know that a card like Font of Vigor is relatively weak because it asks you to spend mana and a card for no impact on the board—it's both tempo disadvantage and card disadvantage! However, a bit of incidental lifegain—say a repeatable source of lifegain built into your deck—can be very helpful. For example, you might choose Nyx-Fleece Ram as one of your cheap defensive creature. Alternatively, you could find a way to include Dismal Backwaters and Radiant Fountains in your mana base.
Once you take control of a game, gaining life is a great way to shut the door on your opponent.
Aggro decks go far out of their way to have reach—a plan for finishing off a weakened opponent in the late stage. Most often, this comes in the form of burn spells, unblockable creatures, or something of the like. Taking away your opponent's reach is a prerequisite for achieving inevitability. In many cases, lifegain does a good job in this respect.
The Consequences of Inevitability
The player with inevitability wants the game to be long and the player without inevitability wants the game to be short. If you have inevitability, you can feel secure in waiting around; if your opponent has inevitability, you should be forcing the action.
The biggest consequence that follows from having inevitability is that you can focus your efforts entirely on defense. All you need to do is sit around and not die, and you can eventually win the game in the late stage, at your convenience. This means that your deck construction and your gameplay might as well be centered around defense.
Let's return to the example of Pearl Lake Ancient. This is a seven-mana card that will be very slow to defend you if your opponent has even a single removal spell. So in a fast matchup, wouldn't the Riverwheel Aerialists be better, just by virtue of being cheaper? Wouldn't a five-mana or a four-mana win condition be even better?
From a deck-construction standpoint, Pearl Lake Ancient is a great win condition, even against fast decks. Oddly enough, this is true despite the fact that it's a slow and inefficient card that you'd never want to draw early in the game. The key is that the presence of one or two Pearl Lake Ancients in your deck provides inevitability. In order to feel comfortable winning a long game, you might need to play with six or eight less-resilient creatures (such as Riverwheel Aerialists), which takes up a lot more space in your deck. Against that super-fast red deck, I'd feel better having two Pearl Lake Ancients and four Drown in Sorrows rather than having to devote six slots to other creatures in order to win the game.
This is why it's common to see control decks playing a very small number of win conditions. Do the bear minimum you need to do in order to achieve inevitability. After that, focus the rest of your deck on early defense. Survive, slow the game down, and a win will eventually fall into your lap.
A Masterpiece of Inevitability
Ivan Floch won Pro Tour Magic 2015 by, in essence, doing nothing. His deck featured no creatures, and just three Planeswalkers, which could only damage the opponent in the slowest and most indirect of ways. Instead, he would simply draw cards, gain life, and recycle his graveyard via his one Elixir of Immortality. Eventually, he would run his opponent out of cards, dole out a slow and painful death via two Mutavaults, or (much more often) the opponent would see the writing on the wall and concede the game.
Floch took the concept of minimal win conditions to the extreme. He didn't even need Elspeth, Sun's Champion! Instead, his deck consisted entirely of card drawing, defense, and of course that single copy of Elixir of Immortality.
Ivan Floch spent the entire tournament waiting. After three days of competition, he'd outwaited all of the other competitors, and was the winner.
By the way he'd constructed his deck, he put the pressure on his opponents to try to close out the game. Nobody was able to do so; instead, they all fell victim to inevitable. Death. Taxes. And Elixir of Immortality.
Well, what are you waiting for?