Diluvian Primordial — ruling 1

You can choose a number of targets up to the number of opponents you have, one target per opponent.

Diluvian Primordial — ruling 2

You cast the cards one at a time, choosing modes, targets and so on. The last card you cast will be the first one to resolve.

Diluvian Primordial — ruling 3

When casting an instant or sorcery card this way, ignore timing restrictions based on the card's type. Other timing restrictions, such as "Cast [this card] only during combat," must be followed.

Diluvian Primordial — ruling 4

If you can't cast one of the target instant or sorcery cards, perhaps because there are no legal targets available, or if you choose not to cast one, it will remain in its owner's graveyard.

Diluvian Primordial — ruling 5

If you cast a card "without paying its mana cost," you can't pay alternative costs such as overload costs. You can pay additional costs such as kicker costs. If the card has mandatory additional costs, you must pay those.

Diluvian Primordial — ruling 6

If a card has {X} in its mana cost, you must choose 0 as its value.

Diluvian Primordial — ruling 7

If an instant or sorcery card you cast this way is countered, it will still be exiled.

Diluvian Primordial — ruling 8

If you cast an instant or sorcery spell with cipher this way, you may exile the card encoded on a creature you control. If you can't, or if you choose not to, the card will end up exiled but not encoded on a creature.

Diluvian Primordial : règles, fonctionnement et interactions (MTG)

Diluvian Primordial is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Flying When this creature enters, for each opponent, you may cast up to one target instant or sorcery card from that player's graveyard without paying its mana cost. If a spell cast this way would be put into a graveyard, exile it instead.

How it works : Diluvian Primordial

Original English text — Wizards of the Coast / Scryfall

#1January 24, 2013· Wizards of the Coast
You can choose a number of targets up to the number of opponents you have, one target per opponent.
No other card is named in this ruling.
#2January 24, 2013· Wizards of the Coast
You cast the cards one at a time, choosing modes, targets and so on. The last card you cast will be the first one to resolve.
No other card is named in this ruling.
#3January 24, 2013· Wizards of the Coast
When casting an instant or sorcery card this way, ignore timing restrictions based on the card's type. Other timing restrictions, such as "Cast [this card] only during combat," must be followed.
No other card is named in this ruling.
#4January 24, 2013· Wizards of the Coast
If you can't cast one of the target instant or sorcery cards, perhaps because there are no legal targets available, or if you choose not to cast one, it will remain in its owner's graveyard.
No other card is named in this ruling.
#5January 24, 2013· Wizards of the Coast
If you cast a card "without paying its mana cost," you can't pay alternative costs such as overload costs. You can pay additional costs such as kicker costs. If the card has mandatory additional costs, you must pay those.
No other card is named in this ruling.
#6January 24, 2013· Wizards of the Coast
If a card has in its mana cost, you must choose 0 as its value.
No other card is named in this ruling.
#7January 24, 2013· Wizards of the Coast
If an instant or sorcery card you cast this way is countered, it will still be exiled.
No other card is named in this ruling.
#8January 24, 2013· Wizards of the Coast
If you cast an instant or sorcery spell with cipher this way, you may exile the card encoded on a creature you control. If you can't, or if you choose not to, the card will end up exiled but not encoded on a creature.
No other card is named in this ruling.
#9January 24, 2013· Wizards of the Coast
If an instant or sorcery card you cast this way goes to a zone other than exile or a graveyard, perhaps because one of its abilities says to put it into its owner's hand, it won't be exiled. This is true even if the card would be put into a graveyard later that turn.
No other card is named in this ruling.