Drawing cards at random from a graveyard

[DrJones]

It looks like Innistrad will have a theme of drawing cards at random from the graveyard. In modern, extended, standard, block and limited, this will likely be achieved by shuffling the graveyard and picking a card at random.

In Vintage, Legacy, EDH, and Prismatic, keeping the graveyard order is compulsory. According to the rules team, we are required to roll a dice to determine which card we pick, or write down a list with all cards in our graveyard before shuffling and picking the card.

The problem with this approach, is that graveyards change size constantly, and in some games there can be +50 cards in the graveyard, specially in some formats and some decks. You'll have to bring 2d10 dice, or something like that, and make sure that every card has the same chance to be picked by this method, or it counts as a cheat. So, if there's 13 cards in your graveyard, you'll have to count first that there are indeed thirteen cards, then roll a 20 side dice, and reroll it until you get a result of 13 or less.

If there's a permanent that allows you to pick a random card from your graveyard, you'll have to count the cards in it, pick the best dice for that size, and roll the dice until you get a valid result every turn, or you manually write down the list, shuffle the graveyard, pick one card, then reconstruct the graveyard, etc. every turn.

Very annoying.

[DrJones]

I contacted Matt Tabak asking for a change on the "pick a random card from a graveyard" effect so that it lets you shuffle your graveyard.

[OurSerratedDust]

Fortunately, these cards won't see much play in Legacy. A lot of people bring dice with them to events, so this shouldn't be a problem very often.

[dontbiteitholmes]

Really they should just get rid of graveyard order matters and for the 3-4 cards that are actually playable where it does matter errata them and ban or errata the rest out of existance.

[Goaswerfraiejen]

Fortunately, these cards won't see much play in Legacy. A lot of people bring dice with them to events, so this shouldn't be a problem very often.

Even with dice, it's sort of difficult if your graveyard has a lot of cards in it (say... 20+). You can always use more than one die, but then you won't ever have a chance of rolling '1'. So really, to be fair, you'd have to divide the cards into piles, roll to see which pile the card comes from, then roll again to see which card it is. But then, that ends up less random than if you were able to roll outright...

[dahcmai]

A six sided and a Ten Sided does the trick. Use the 6 sided for the tens spot and the 10 sided for the 1's. Re-roll the 6 if you need to. Simple enough really. Use a 4 sider if smaller. Odds and evens, cmon most Magic players are quite good at math.

[Goaswerfraiejen]

A six sided and a Ten Sided does the trick. Use the 6 sided for the tens spot and the 10 sided for the 1's. Re-roll the 6 if you need to. Simple enough really. Use a 4 sider if smaller. Odds and evens, cmon most Magic players are quite good at math.

That still makes it impossible ever to draw the card at the bottom of your graveyard, though. In fact, using a 6er for the tens makes it impossible to draw anything below the tenth card (assuming 10=0). So if I have 32 cards in my graveyard, that method only allows me to draw from the top 22 cards of my graveyard.


FWIW, I own one six-sided die. I don't play other games, so don' really know what kind of dice are available/most of you have.

[boneclub24]

FWIW, I own one six-sided die. I don't play other games, so don' really know what kind of dice are available/most of you have.

You can get D10s with a 0 for the 10.

[dyzzy]

That still makes it impossible ever to draw the card at the bottom of your graveyard, though. In fact, using a 6er for the tens makes it impossible to draw anything below the tenth card (assuming 10=0).

No. You just subtract 1 from the 10's digit. Using this method, you get 10-69, so if you subtract 10 from the number, it turns into 00-59. (Also, you can add 1 to the final result to get 01-60.) But this really shouldn't require that much math.

[Goaswerfraiejen]

No. You just subtract 1 from the 10's digit. Using this method, you get 10-69, so if you subtract 10 from the number, it turns into 00-59. (Also, you can add 1 to the final result to get 01-60.) But this really shouldn't require that much math.

There we go, that works better. Thanks for the suggestion.

[Malchar]

That still makes it impossible ever to draw the card at the bottom of your graveyard, though. In fact, using a 6er for the tens makes it impossible to draw anything below the tenth card (assuming 10=0). So if I have 32 cards in my graveyard, that method only allows me to draw from the top 22 cards of my graveyard.


FWIW, I own one six-sided die. I don't play other games, so don' really know what kind of dice are available/most of you have.

I just lost a little faith in humanity after reading this post. I like to assume that most Magic players are also pretty good at math. Everyone should be able to figure out a way to select a card at random from a graveyard of any size using only a d6 or coin for that matter. It is quite easy really. Besides, at any given tournament, someone nearby always has a d20, or two d10's if you want it to be as easy as possible.

[Goaswerfraiejen]

I just lost a little faith in humanity after reading this post. I like to assume that most Magic players are also pretty good at math. Everyone should be able to figure out a way to select a card at random from a graveyard of any size using only a d6 or coin for that matter. It is quite easy really. Besides, at any given tournament, someone nearby always has a d20, or two d10's if you want it to be as easy as possible.

I'm so sorry. I hope you can find it in your immense heart to forgive me one day. I hadn't realized it was so easy to select a card at random from a large graveyard with only a D6. Had I been better at math, I'd have realized that 6 is a larger number than 32.

Obviously it's doable. The question was only with how much ease (in other words, with as few materials and in as few steps as possible). I naïvely assumed most Magic players are pretty good at reading. Again, so sorry to have let you down.

[Phoenix Ignition]

Rolling two dice (for each digit of graveyard card) doesn't actually give you a random card, it weighs some cards heavier than others.

Example: You have 31 cards in your graveyard. You elect to roll one 6 sided dice to see which tens digit you get (subtracting 1 from it, so if you roll a 1 you are then going to pick cards 1-9), rerolling any non-important tens digit (so reroll when it is a 5 or 6 because you don't have that many cards in the graveyard). Rolling a 1, 2, or 3 is not a problem as the 10 cards in those digits are all evenly weighted while rolling a 10 sided dice for your second digit. Rolling a 3 however automatically makes your 30th and 31st cards the only choices to pick from. That means that your 0-9, 10-19 and 20-29 cards are all less likely to be chosen (and therefore you are not following the rules of the card). It makes the 30th and 31st cards each 12.5% likely to be drawn while the 1-29th cards are each 2.5% likely to be drawn.

If you have a number of cards in graveyard that is divisible by one of the dice you have (divisible by a 6 or a 10) it would be easy enough to find a way, but given a larger prime number things could get dicey (har har). It might even require writing down the place of every card in the graveyard and then just shuffling and picking one and then reordering.

tl;dr: Choosing a random card is not as easy as you may have previously thought.

No matter what though, this looks hilarious.

[Gheizen64]

Rolling two dice (for each digit of graveyard card) doesn't actually give you a random card, it weighs some cards heavier than others.

Example: You have 31 cards in your graveyard. You elect to roll one 6 sided dice to see which tens digit you get (subtracting 1 from it, so if you roll a 1 you are then going to pick cards 1-9), rerolling any non-important tens digit (so reroll when it is a 5 or 6 because you don't have that many cards in the graveyard). Rolling a 1, 2, or 3 is not a problem as the 10 cards in those digits are all evenly weighted while rolling a 10 sided dice for your second digit. Rolling a 3 however automatically makes your 30th and 31st cards the only choices to pick from. That means that your 0-9, 10-19 and 20-29 cards are all less likely to be chosen (and therefore you are not following the rules of the card). It makes the 30th and 31st cards each 12.5% likely to be drawn while the 1-29th cards are each 2.5% likely to be drawn.

If you have a number of cards in graveyard that is divisible by one of the dice you have (divisible by a 6 or a 10) it would be easy enough to find a way, but given a larger prime number things could get dicey (har har). It might even require writing down the place of every card in the graveyard and then just shuffling and picking one and then reordering.

tl;dr: Choosing a random card is not as easy as you may have previously thought.

No matter what though, this looks hilarious.

That's why you roll both dices together instead of one at once. That way you don't have a problem. If you roll a 32, reroll.

It's not really rocket science. Or get a d100 and get over it.

[Gheizen64]

Rolling two dice (for each digit of graveyard card) doesn't actually give you a random card, it weighs some cards heavier than others.

Example: You have 31 cards in your graveyard. You elect to roll one 6 sided dice to see which tens digit you get (subtracting 1 from it, so if you roll a 1 you are then going to pick cards 1-9), rerolling any non-important tens digit (so reroll when it is a 5 or 6 because you don't have that many cards in the graveyard). Rolling a 1, 2, or 3 is not a problem as the 10 cards in those digits are all evenly weighted while rolling a 10 sided dice for your second digit. Rolling a 3 however automatically makes your 30th and 31st cards the only choices to pick from. That means that your 0-9, 10-19 and 20-29 cards are all less likely to be chosen (and therefore you are not following the rules of the card). It makes the 30th and 31st cards each 12.5% likely to be drawn while the 1-29th cards are each 2.5% likely to be drawn.

If you have a number of cards in graveyard that is divisible by one of the dice you have (divisible by a 6 or a 10) it would be easy enough to find a way, but given a larger prime number things could get dicey (har har). It might even require writing down the place of every card in the graveyard and then just shuffling and picking one and then reordering.

tl;dr: Choosing a random card is not as easy as you may have previously thought.

No matter what though, this looks hilarious.

That's why you roll also the second dice before deciding. That way you don't have a problem. If you roll a 32, reroll.

It's not really rocket science. Or get a d100 and get over it.

[bruizar]

just reading this thread gives me a headache. Let's make a gentlemen agreement not to use any of those cards in legacy or vintage.

That, or include a shuffle clause so we can play it by presenting hand to opponent, Hypnotic Specter style.

I'm seriously wondering wtf is up with RND. Doublefaced cards, proxies, and the use of different sized dice depending on graveyard size? err...