Thoughtseize You

Reid offers up a detailed primer on Thoughtseize, an iconic Magic card that is being reprinted in Theros, covering everything from deckbuilding to sideboarding to gameplay.

Thoughtseize has come to be one of the most iconic cards in Magic. Though the card itself has not been legal in every format, the Thoughtseize effect is more or less ubiquitous in cards like Duress, Inquisition of Kozilek, and dozens of others. Now, with Thoughtseize being reprinted in Theros, its presence will be felt more than ever, and its status as a tournament staple is all but guaranteed for the next few years. Understanding how to use Thoughtseize will be integral to the success of any tournament player. Today I’ll cover everything you need to know about Thoughtseize, from deckbuilding to sideboarding to gameplay.

The Risks Of Thoughtseize

Trading One For One

The first step is to understand what Thoughtseize really accomplishes in a game of Magic. While it’s a hyperefficient card that sees extensive play even in Legacy and Vintage, there are some heavy costs associated with the card as well.

Thoughtseize, in terms of card advantage, represents a one-for-one trade—no advantage is gained directly. Therefore, step one in considering Thoughtseize is to think about whether your deck wants to trade one for one. Good candidates for Thoughtseize along this metric might be Jund or U/B Control. However, not every deck will fit this bill.

A common pitfall that I see among newer deckbuilders is a draw towards B/R decks that feature both a lot of burn and a lot of Thoughtseize effects. This is natural because black and red are a likely pair according to Magic’s flavor and those are among the most iconic effects that each color has to offer.

However, the reality is that Thoughtseize is exactly what a burn deck does not want. The strength of burn is that it’s difficult for the opponent to interact with through ordinary means, so if you add Thoughtseize to the deck in the place of a card that would otherwise contribute to your game plan, you’re really just giving your opponent exactly what they want—a way to trade off cards against you.

In my experience, such decks are excellent at getting the opponent down to five life but are not the best at actually winning games.

The same is true of ramp strategies, like Mythic and Wolf Run Ramp. These decks devote such a high proportion of their cards to mana that each nonland card must have a very high impact on the game in order for the strategy to work. So a card like Thoughtseize, the goal of which is to trade with an opposing spell (of which the opponent has many more than you), is not really what you’re looking for.

These decks can still consider Thoughtseize, especially as a sideboard card, for specific reasons that I’ll get into below, but it’s important to understand that its inclusion comes at a dear cost.


For decks that do want to trade one for one, Thoughtseize is appealing in its ability to accomplish that efficiently and reliably. However, it’s still not perfect for every situation. In terms of tempo, Thoughtseize does not affect the board and trades with a card which the opponent has not yet invested mana into—strictly speaking, casting a Thoughtseize puts you a little behind.

Consequently, Thoughtseize is quite poor against a deck with a lot of redundancy. Redundancy, in the context of a Magic deck, means that cards are very replaceable. Splinter Twin does not have much redundancy because it needs to assemble one copy of Deceiver Exarch, one copy of Splinter Twin, and one cheap way to protect the combo. Thoughtseize is excellent against such a deck because when you take away the opponent’s one Exarch, they have very few cards that they can draw that will help them recover from the loss and their deck functions poorly if they’re unable to do so.

The opposite example is a very basic creature deck—think White Weenie or Mono-Green Aggro. Thoughtseize would be at its worst against a deck of twenty Forests and forty Kalonian Tuskers because it’s overwhelmingly likely that you would take one Kalonian Tusker out of the opponent’s hand and they would simply play a different one instead. The Thoughtseize effect is doubly bad against such a deck because you cannot effectively attack their hand and casting Thoughtseize does not help you keep up with what’s on the board. You’d much prefer to have a Doom Blade, which answers a creature that the opponent has already spent mana on, or you’d prefer to have your own creature, which will help you under any circumstances.


What I haven’t yet mentioned is the chance of missing with your Thoughtseize, which is a huge risk that I consistently see players underestimate. Games of Magic are won and lost on small margins; when you mulligan, when you get two for oned, or when anything else happens to set you behind on cards, the pressure falls on you to do something great in order to pull yourself back to parity. If you cannot and both players have comparable draws, you will lose the game. I don’t think I’d be able to overstate how bad it is to miss on a Thoughtseize, particularly in Limited or in a grindy matchup like a Jund mirror. For you to want Thoughtseize in your deck, circumstances must be such that the risk of missing is very low or the rewards of hitting are very high.

The risk of missing is the main reason why the card Thoughtseize tends to outshine other versions of the Thoughtseize effect. It’s one of the reasons that I’ve never registered Appetite for Brains in a Constructed tournament, and it’s the reason why Duress is typically relegated to sideboard.

Coming Down To Topdecks

Let’s compare the Thoughtseize effect to the similar and equally iconic Counterspell effect.

The advantages of the Thoughtseize effect are:

  • You can cast Thoughtseize at your own convenience, while Counterspell must be used in a specific window.
  • You get to see the opponent’s hand.
  • Thoughtseize and similar cards tend to be quite cheap.
  • Some cards cannot be easily countered.

The advantages of the Counterspell effect are:

  • You answer a card that the opponent has invested mana into.
  • You protect yourself from topdecks.

You’ll come to regret the inclusion of Thoughtseize any time the game stalls out and players begin playing off the top of their libraries. Drawing Thoughtseize when the opponent has no cards in their hand (or only lands) is much the same as missing with it.

It’s an unfortunate quality of Thoughtseize that it helps draw the game towards that topdeck situation while also being an abysmal topdeck in itself.

Ask yourself during deck construction and during sideboarding how likely it is for the game to come down to a topdeck situation; indeed, sometimes it’s your goal for the game to get to this point (Jund, Junk, Pox, and similar decks frequently have this goal). If it seems likely, then ask yourself how much you can afford to dilute your deck with cards that are so bad to draw in the lategame.

A simple way to weigh the risks and rewards of Thoughtseize is to consider it a card that’s excellent to have in your opening hand and poor to draw at any other time. Before you start playing, try to predict how many turns the game is likely go, and you’ll get a number for how many cards you’re going to see in a typical game. Compare the number of cards that you’ll draw in your opening hand (hopefully seven) to the number of cards you’ll draw off the top of your deck in the course of the game.

When this ratio is high, as it is against a fast combo deck, Thoughtseize is more likely to shine. While it might not be intuitive, I’ve found Inquisition of Kozilek to be an excellent card in Modern Jund against decks like Affinity and Burn (the life loss on Thoughtseize can be a large cost and should be evaluated on a case-by-case basis) for exactly this reason. When the ratio is low, as it is in something like a Jund mirror, Thoughtseize is more likely to be a liability.

For years, I’ve felt confident in my ability to win Jund mirrors in Modern. My secret is that I sideboard out every last Thoughtseize, Inquisition of Kozilek, and Duress that I have in favor of cards that are more powerful to rip off the top of my deck. Almost invariably both players have empty hands by turn 4 or 5, and against an opponent who has six dead draws in their deck, my chances to win a game from that point become quite high the longer the game drags on.

To recap, be wary of including Thoughtseize in decks that do not want to trade one for one. Thoughtseize has lower value in a metagame full of decks with a lot of redundancy. Look to sideboard out