Oracle of Bones — ruling 1

For effects that check which player put counters on the entering creature, the player chosen to pay tribute puts those counters on it, not the creature’s controller.

Oracle of Bones — ruling 2

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

Oracle of Bones — ruling 3

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

Oracle of Bones — ruling 4

If you choose to cast a split card with fuse without paying its mana cost, you may cast both halves.

Oracle of Bones — ruling 5

If the opponent pays tribute, the creature will enter the battlefield with the specified number of +1/+1 counters on it. It won’t enter the battlefield and then have the +1/+1 counters placed on it.

Oracle of Bones — ruling 6

If you want to cast a card this way, you cast it as part of the resolution of the triggered ability. Timing restrictions based on the card’s type (such as sorcery) are ignored. Other casting restrictions (such as “Cast [this card] only before attackers are declared”) are not.

Oracle of Bones — ruling 7

If the triggered ability has a target, that target will not be known while the creature spell with tribute is on the stack.

Oracle of Bones — ruling 8

Players can’t respond to the tribute decision before the creature enters the battlefield. That is, if the opponent doesn’t pay tribute, the triggered ability will trigger before any player has a chance to remove the creature.

Oracle of Bones : règles, fonctionnement et interactions (MTG)

Oracle of Bones 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

Haste Tribute 2 (As this creature enters, an opponent of your choice may put two +1/+1 counters on it.) When this creature enters, if tribute wasn't paid, you may cast an instant or sorcery spell from your hand without paying its mana cost.

How it works : Oracle of Bones

Original English text — Wizards of the Coast / Scryfall

#1April 18, 2017· Wizards of the Coast
For effects that check which player put counters on the entering creature, the player chosen to pay tribute puts those counters on it, not the creature’s controller.
No other card is named in this ruling.
#2February 1, 2014· Wizards of the Coast
If the card has in its mana cost, you must choose 0 as its value.
No other card is named in this ruling.
#3February 1, 2014· 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, however, 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.
#4February 1, 2014· Wizards of the Coast
If you choose to cast a split card with fuse without paying its mana cost, you may cast both halves.
No other card is named in this ruling.
#5February 1, 2014· Wizards of the Coast
If the opponent pays tribute, the creature will enter the battlefield with the specified number of +1/+1 counters on it. It won’t enter the battlefield and then have the +1/+1 counters placed on it.
No other card is named in this ruling.
#6February 1, 2014· Wizards of the Coast
If you want to cast a card this way, you cast it as part of the resolution of the triggered ability. Timing restrictions based on the card’s type (such as sorcery) are ignored. Other casting restrictions (such as “Cast [this card] only before attackers are declared”) are not.
No other card is named in this ruling.
#7February 1, 2014· Wizards of the Coast
If the triggered ability has a target, that target will not be known while the creature spell with tribute is on the stack.
No other card is named in this ruling.
#8February 1, 2014· Wizards of the Coast
Players can’t respond to the tribute decision before the creature enters the battlefield. That is, if the opponent doesn’t pay tribute, the triggered ability will trigger before any player has a chance to remove the creature.
No other card is named in this ruling.
#9February 1, 2014· Wizards of the Coast
The triggered ability will resolve even if the creature with tribute isn’t on the battlefield at that time.
No other card is named in this ruling.
#10February 1, 2014· Wizards of the Coast
The choice of whether to pay tribute is made as the creature with tribute is entering the battlefield. At that point, it’s too late to respond to the creature spell. For example, in a multiplayer game, opponents won’t know whether tribute will be paid or which opponent will be chosen to pay tribute or not when deciding whether to counter the creature spell.
No other card is named in this ruling.