Technically, you can name any Magic card you want with Pithing Needle. However, to actually stop your opponent from activating an activated ability, you’ll have to name the card that is its “source” — in other words, the card that “has” the ability.

A card like Underworld Connections sure looks like the source of an ability, seeing how the ability’s text is written on the Connections; but a closer look reveals that what it’s actually doing is granting the ability to something else (the land that it’s enchanting). So, in order to stop Underworld Connections out of a Mono-Black Devotion deck, go against your intuition and name basic Swamp. The Swamps will still be able to tap for mana, but none of them will be able to tap to draw cards.

In a deck with lands other than basic Swamps, this becomes more tricky. If you name Swamp with a Pithing Needle because the opponent has one Underworld Connections on a Swamp, that player can cast a second Underworld Connections on his Temple of Deceit, and it will function just fine. The worst thing you can do, of course, is actually naming “Underworld Connections” with Pithing Needle, as that will never do anything useful.

Bonus tournament tip: As mentioned above, asking a judge “Can I name Card X with Pithing Needle” isn’t going to get you a very helpful answer. Instead, you should ask “Does Card X have an activated ability, that isn’t also a mana ability?” This clarifies to the judge exactly what you want to know (if the answer is ‘no’, name something else!) without making it seem like you’re asking the judge whether a given play is good or bad for you.

Today’s Rules Tip written by Jen Wong