You have a Shock and your opponent has a Grizzly Bears that you want to kill. It is your first main phase. Do you target it now, or wait? And if so, wait until when; your combat phase, your second main phase, their upkeep, their combat step, their end of turn?
Whenever this or a similar situation comes up you must consider certain things.
In a duel there are four kinds of information. The information that you have exclusively (say, the cards in your hand), the information that your opponent has exclusively (say, the cards in their hand), the information shared by both players (say, the board), and the information shared by neither player (say, the top of your deck).
All of this information is relevant. With more information, you're able to make better plays.
Plays are made to maximize the information private to yourself, and minimize the information private to your opponent. Plays are also made with private information in mind, whether it is your own, or something your opponent might potentially do.
The greater the proportion of information you have access to, the more able you are to create unfavorable situations for your opponent. Sometimes it will be important to preserve information, and sometimes it will be important to acquire it.
If your opponent had known this information (that you have Shock), they would not have made this play. If you had revealed information sooner (played Shock early), your opponent would not have had the opportunity to make this play.
Under different circumstances acquiring information might motivate action sooner than later. You're at 2 life and your opponent's at 4. Your opponent also has a Grizzly Bears, but it's tapped. If you play the Shock now, you find out immediately whether your opponent has a Giant Growth, or even something like a countering spell. This information informs your attack for the turn. If they can save their Bears, you should hold back, if they can't, you should attack.
Factoring the information unknown to both players adds an entire other dimension.
By waiting, you're giving your opponent more information. Now they know the card they've drawn this turn. (More than that, they can use it—but let's hold that thought for now.) By acting sooner, you deny yourself information. If you wait until your next turn, you will know your next draw step. But some information (IE, your opponent 'knowing' the top card of their deck), is less important than other information (whether your opponent has the crucial trick in hand).
Often it is information about specific cards that motivates you to make one play and not the other. If you think your opponent has a Mending Hands that might suggest an entirely different play than if you think your opponent has Giant Growth.
In choosing how to act you must at once balance the likelihood your opponent has once card over the other, based on how they've played the game so far, and also based on the format (are there twice as many "Giant Growth" effects as there are "Mending Hand" effects? What colors does your opponent even have access to?)
Information is a constant consideration, but not one that necessarily motivates any particular play (waiting or acting). In general, you want to wait until you have a reason to act. But there are many reasons to act, with varying levels of incentive.
In short, information is a slippery consideration. There are plenty of errors to make, but they are rarely (though sometimes are) game defining. It is difficult to manage even for the best players. They aim to make consistently good general decisions.
The status of resources regularly changes. Every turn has an untap step, and a new card drawn. A player has the ability to attack with creatures on his turn, but not on his opponent's. Deck size diminishes.
Plays are often made to either best manage your own resources, or to best navigate or disrupt your opponent's.
One reason you might wait to ShockGrizzly Bears is to disrupt your opponent's mana. Consider a situation in which you think your opponent might have a Mending Hands, and they already have a Plains untapped. If you Shock their Bears now, they will save it and have all of their mana at their disposal for their next turn. If you wait until their upkeep, then if they save the Bears at least they will have one less mana to spend.
The reason you might wait until their upkeep, and not later, is because of the card draw. This way, you don't risk them drawing the Mending Hands (or something else) if they don't already have it.
In the case of waiting in case your opponent plays Blanchwood Armor... what if they draw Giant Growth? Now when you try to Shock the bears, it's going to get Giant Growth and hit you for even more damage. By waiting you've cost yourself both the Grizzly Bearsand 5 damage! Which is a better decision? It depends.
There are other risks involved in waiting. On your opponent's turn they have the ability to attack. Let's say that they have Giant Growth instead of Mending Hands. If you use the Shock now, on your own turn, then Giant Growth doesn't result in any extra damage to you. If you wait until their turn, then it might mean an extra 3 damage to you.
Beyond the cyclical resource replenishment stages that are often important to navigate, there is also the issue of more permanent resources. How many cards does your opponent have in hand? How much land do they have in play?
If your opponent has a full hand, making plays while they have all their mana untapped is riskier; because they have a higher likelihood of having a juicy response.
If your opponent has heaps of mana, then plays made to disrupt mana (with other risks) are less attractive.
If you have heaps of mana, then you lose incentive to play Shock at your opponent's end of turn (your last chance before you untap), and gain incentive to simply wait for the most opportune time.
If your opponent has a tapped creature with a relevant ability (Samite Healer), perhaps it's best to act now?
It is important to always consider the status of resources.
What are some of the factors must you consider?
- Should you play this Shock to acquire information? What information is important to acquire right now? How could you acquire it?
- Should you preserve this information? Does this look like a profitable or safe situation in which to preserve information?
- What specific cards do you have in mind and how do they motivate you to play?
- Do they have mana untapped?
- Is it worth waiting until after they draw?
- Is their ability to attack relevant? How relevant?
- How many cards do they have in hand?
- How many lands do they have in play?
- What are the life totals?
- Are there any specific cards worth considering? (Say, a Thallid Germinator with only 2 counters.)
This may seem overwhelming, but in an actual game a decision usually boils down to only a few considerations, while all the rest are clearly not relevant.
You have Shock in hand, and your opponent has a Grizzly Bears in play. You have no creatures in play, and both players have all of their (4 each) land untapped. Both players are at 20 life and have 5 cards in hand. Your opponent has Swamps and Forests in play.
You could play the Shock early to see if your opponent has anything to do about it (acquire information), but there doesn't seem to be any reason to.
You could wait to both preserve information and acquire more in case they play a creature enchantment or a more desirable creature to kill before the combat phase.
Do you have any idea about specific cards that your opponent could play that influence you one way or another? If this is a core set Draft or Sealed Deck, Black doesn't have much—maybe a creature enchantment that you know your opponent is playing? Green has both creature enchantments and pump spells. Do you have any idea which they have more of, or what they might be holding?
They have mana untapped, so if they have pump, they can save the Bears if they want. You could wait until their upkeep to disrupt a mana, but then you'd be costing yourself 5 damage and the Bears if they did have the Growth—seems like a bad trade. You could wait until their combat step, and potentially bag a 2 for 1 if they play a creature enchantment. But this, in addition to potentially costing you 5 and a Bears, also allows your opponent the chance to draw the Growth if they don't already have it.
Your opponent doesn't have much land in play, and has a full hand; disrupting land is valuable at this stage. But the only circumstance in which you actually disrupt your opponent's mana involves you taking 5 damage and them keeping the bears; a poor trade.
Your life total is high; you can afford to take a bit of damage, but 5 is a lot even at 20 life. There are no specific-on board cards to consider.
So what does this situation boil down to?
You can either play the Shock during your second main phase, considering Giant Growth or a similar trick. Or, you can wait until your opponent's combat step (before you would take damage), considering a creature enchantment. Unless you have reason to believe your opponent is likelier to have one more than the other (and you often will), best to err away from the worst case scenario. If I felt I needed to kill the creature, I'd probably Shock the Bears on my turn in this case.
Let's change details.
You have a 1/3 in play and their land is tapped.
The reason to wait would be to nab either a creature enchantment, or a pump-spell. (If they attack with Bears, you can block with the 1/3. If they pump it, you can Shock it first. In short, their ability to attack is much less relevant.)
In this case, if you have reason to believe they have either a trick or a creature enchantment, you will be more inclined to wait.
Since they have the full 7 cards, it's likely they have one or the other. If they had 0 cards in hand, you would be more inclined to Shock now.
One risk is if they have both a creature enchantment and a pump spell (and of course by waiting you may allow them to draw the missing piece). They untap, play the enchantment, you Shock, and then they pump in response.
So, what does the situation boil down to? You can Shock the Grizzly Bears now and attack for 1. Or, you can wait, until they either play a creature enchantment, play a pump spell after you've blocked, or until their end of turn, in exchange for a number of risks.
In this situation, I'd probably wait on the Shock.
What if they also have a tapped Samite Healer in play?
Now, if you've decided it's the Bears that must die, it's important to kill the Bears on your turn. As soon as your opponent untaps your Shock won't help against either pump or a creature enchantment.
Even small changes to details (like the color of mana your opponent has available) make a dramatic difference.
These are simplified examples, and the risk/reward of acting/waiting usually extends even deeper. My goal is only to introduce to you to these factors so you can start seeing the kinds of things more experienced players take into account. They are knit tightly into the fabric of any game and most decisions can be broken down and analyzed in this way. Some plays are strictly superior to others (for instance, in a certain case there might be no disadvantage, only possible advantage, for waiting on the Shock until your upkeep). Others require a decision. (My main phase or your combat step?) Ultimately, with such layered considerations, you must develop a sense for which plays maximize profit and/or minimize loss. Sometimes it's very close. Even the best players struggle with these decisions, but it's part of what makes Magic so much fun.
Next week: managing manascrew.