Pair o' Dice Lost

Official rulings

1. Results can be numbers not ordinarily possible on a six-sided die. Spells like Scooch can change the result to 0 or 7, for example. (2022-10-07)
2. Some effects may modify the result of a die roll. This may be part of the instruction to roll a die, or it may come from other cards. Anything that references the "result" of a die roll is looking for the result after these modifications. (2022-10-07)
3. If Pair o' Dice Lost resolves, it will be exiled, even if you don't return any cards to your hand. (2022-10-07)
4. If a die is rerolled, the original roll essentially never happened: it doesn't cause any abilities to trigger, and no effect that cares about die rolls will consider it. (2022-10-07)
5. Pair o' Dice Lost doesn't target any of the cards in the graveyard. You choose which cards you're returning to your hand, if any, after rolling the dice. (2022-10-07)
6. Each die is identified by the number of faces it has. A six-sided die is a die with six equally likely outcomes: 1, 2, 3, 4, 5, and 6. The roll must be fair. Although physical dice are recommended, digital substitutes are allowed except in cases where the physical die is required for the effect. (2022-10-07)
7. You can return any number of cards with mana value 0 (such as land cards) from your graveyard to your hand regardless of the results. (2022-10-07)
8. Something in the game must tell you to roll a die. If you roll a die for any other reason (to simulate a coin flip, to choose pizza toppings, to create alternate timelines), that roll doesn't count. (2022-10-07)
9. If an ability triggers "whenever you roll a die," it will trigger whenever you roll any die, including the planar die. This is a change from previous Un- rules. Some abilities use the result to determine part of the effect. If you get a non-numerical result (currently just the planar die, but the future is long), that part of the effect won't do anything. (2022-10-07)