Good morning and welcome back! Today we’re talking about a card from House Dimir- the Thief of Sanity. It’s fairly straightforward: Whenever it smacks your opponent with combat damage, you get to look at the top 3 cards of their library and exile one of them face-down, putting the other cards in the graveyard. Now, normally nobody can look at cards that are exiled face-down, but Thief gives you permission to look at that card while it’s in exile, as well as permission to cast it (and allowing you to spend mana as if it were any color TO cast it, so you can get full value even if you’re up against a Red/Green deck). So YOU can see the cards your Thief has stolen, but your opponent can’t, which lets you set up some nasty surprises for them. But what happens if your opponent throws a topdecked Act of Treason at your Thief, and hits you with it? Well, they’ll look at the top 3 cards of YOUR library, exile one face-down hidden from you, and be able to cast it for as long as it remains exiled.
Here’s where things get dicey. Other cards like Grimoire Thief have a separate “you may look at cards exiled with Grimoire Thief” ability, rather than the permission being baked into the part that exiles the card. What happens if your opponent kills your Grimoire Thief? Well, since you were allowed to look at the cards it exiled, that permission lingers long after the ability stops existing. Even without Grimoire Thief on board, you can keep looking at all the cards it exiled, because you were allowed to look at them before. But that also means if your opponent hit a Grimoire Thief with Act of Treason, THEY would be able to look at those exiled cards. And even if they were only able to look at those cards for the span of a turn, the “if you could ever look at this face-down exiled card, you can keep looking at it all game as long as it’s in exile” rule kicks in for them too. But that’s NOT the case with Thief of Sanity- since the permission to look at the card is on a per-card basis, and baked into the trigger that exiles the card, there’s no crossover. You won’t be able to look at the card your opponent exiled with Thief of Sanity, and they won’t be able to look at the cards YOU exiled. Important distinction!