A Wizards forum thread had an interesting question that was left unanswered. If I have only two black mana available, can I cast Fatal Lore if my opponent has a Spellwild Ouphe on the battlefield? The issue is it is a legal play only if my opponent chooses the destroy creatures option (since I could target the Ouphe, making it cost two lest to cast).

  • Nice question. Things do work in the right order to enable this question: first you make mode choices, then you choose targets, then you pay mana. May 19, 2015 at 1:07
  • @doppelgreener It's worth noting that most of the other similar situations (that theoretically worked for the same reason) in that thread were shot down as misuses of rule 717.
    – murgatroid99
    May 19, 2015 at 1:14
  • 1
    On the other hand, this specific case doesn't really have a one-sided upside - you're basically revealing a card from your hand and offering the two creatures for three cards deal to your opponent, so it's not an abuse of the rules like a lot of the other situations.
    – Cascabel
    May 19, 2015 at 2:08

2 Answers 2


Since it is a legal play under some outcomes of the process of casting it, it is a legal play. If your opponent chooses the mode where you draw cards, it will become an illegal spell and the game will be reverted to the state it was in before you began casting it.

The precedent for this comes from a card specific ruling on Selvala, Explorer Returned:

If you activate Selvala’s ability while casting a spell, and you discover you can't produce enough mana to pay that spell’s costs, the spell is reversed. The spell returns to whatever zone you were casting it from. You may reverse other mana abilities you activated while casting the spell, but Selvala’s ability can't be reversed. Whatever mana that ability produced will be in your mana pool and each player will have drawn a card.

From this, we can tell that you are allowed to cast spells you might be able to pay for.

As Hackworth and various members on the forum point out, the rules do not explicitly prevent you from attempting to cast spells you have no way of paying for in any circumstance, but doing so doesn't ever help you. At best, it reveals a card in your hand with no other consequence. At worst, it could get you disqualified in a tournament for repeat offenses of slow play or cheating (if you are attempting to cast an illegal spell to make an opponent reveal information in their reaction).

  • 3
    Good answer, I liked the Selvala citation. Just a clarification though: Casting a spell or activating an ability is considered legal until the opposite is shown, not the other way around as your first statement seems to imply. There is no obligation to "look ahead" and determine whether there is an illegal step before you get to such a point. Of course, if you make it a habit to make illegal plays over and over, you might be punished for slow play or something in high REL, but that's another matter which the CompRules don't care about.
    – Hackworth
    May 19, 2015 at 11:59
  • @Zags May wish to look to rule 717 for a reference to the Comp Rules for this.
    – Waterseas
    May 19, 2015 at 14:11
  • @Hackworth Actually the rules do go into that. If you have infinite mana, and Fatal Lore is the only card in hand: "716.3. Sometimes a loop can be fragmented, meaning that each player involved in the loop performs an independent action that results in the same game state being reached multiple times. If that happens, the active player (or, if the active player is not involved in the loop, the first player in turn order who is involved) must then make a different game choice so the loop does not continue."
    – Waterseas
    May 19, 2015 at 14:16
  • @Waterseas Yes, but that's the limited case of doing the same thing over and over again. I meant in the general case, where a player could play a different spell/ability illegally every time.
    – Hackworth
    May 19, 2015 at 14:35
  • @Hackworth Hmm, not fully sure I follow.
    – Waterseas
    May 19, 2015 at 14:49

You should be able to cast it. When you declare that you want to cast it, you don't yet know whether it will be possible to pay, but it could be possible, depending on your opponent's choice. If your opponent chooses that you draw 3 cards, you won't be able to continue casting it. But if your opponent chooses the destruction mode, then you will be able to finish casting it.

It wouldn't make sense to prevent you from attempting to cast the spell simply because it's possible that you will fail to cast it, if it is also possible that you will be able to cast it.

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