I have a question regarding Prognostic Sphinx and its second ability (as you'll probably be able to tell, I'm very new to this game).

According to its second ability, I can discard a card so that it "gains hexproof until end of term" at the cost of tapping it.

I don't know if I'm reading this correctly or not, but does this mean I can only tap it during my turn and my turn only, and as soon as my opponent begins his next turn, it becomes untapped, loses hexproof, and is therefore susceptible to spells anyways? If this is the case, what's the usefulness of this ability other than protecting it during my turn?

2 Answers 2


Prognostic Sphinx's ability has no restriction on timing, so you can activate it whenever you have priority. This includes on your opponent's turn, or in response to another spell or ability.

Abilities that have timing restrictions will always state it, either directly on the card or in the rules for that ability. For example, the rule for Outlast has a clause "Activate this ability only any time you could cast a sorcery." This clause restricts when you can activate the ability.

Creatures do not untap on your opponent's turn unless an effect specifically untaps them.

Tapping Prognostic Sphinx is not part of the cost of activating the ability. It is an effect. This is important because it means you can activate the ability even when Prognostic Sphinx is already tapped (although the instruction to "Tap it." won't actually do anything).

  • 6
    Re "Abilities that have timing restrictions will always state it", Though it may be in the rules for keyword abilities (e.g. Equip)
    – ikegami
    Nov 6, 2017 at 21:51
  • That caught my eye too, ikegami. My first instinct was Planeswalker abilities.
    – corsiKa
    Nov 6, 2017 at 23:33
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    @corsiKa I edited the answer before you posted your comment. Is there still a point that you think could use more clarification?
    – Rainbolt
    Nov 6, 2017 at 23:55
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    "Tap it" being an effect rather than a cost also means you can use the ability while it is "summoning sick"
    – Caleth
    Nov 9, 2017 at 13:31

The basic idea is that you can counter your opponent's spells and abilities with it. I think the idea you're missing is that any ability on a card acts at instant speed (just like an instant spell) so you can use it anytime you have priority (unless the card specifically states otherwise). So the idea is that you have to use the ability in response to them using a powerful spell to guarantee you get some value.

Learning what priority is and how to use it is a little complicated but the basic idea is whenever a player does something their opponent gets to react. Though how you react is restricted, usually only instant spells or unrestricted abilities actually work as ways to surprise or counter your opponent.

So, here's an example:

  1. I cast Hero's Downfall targeting your Sphinx
  2. In response, you activate the second ability, giving it hexproof.
  3. Hero's Downfall tries to resolve, but it now has an illegal target (due to it being hexproof) and is countered.

Congratulations, you've discarded your worst card in your hand to counter a very effective removal spell. Not a bad trade. The real power is you can keep doing this as long as you have a card to discard. So if I have 4 removal spells but you have 4 lands in your hand then I cannot kill your sphinx.

The only real downside here is if I'm an aggro deck I can use those spells to force you to tap him so you can't block. That strategy only buys me 1 turn per spell though, so it's not very good for me.

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