Welcome back! Eldritch Moon gave us a lot of scary colorless cards, the scariest of which is Emrakul, the Promised End. Emrakul is the newest in the line of cards that let you control another player during their turn (colloquially called “Mindslaver” effects, after the first such card printed in Mirrodin block!). While it hasn’t been that long since we had Worst Fears in Standard, it’s much more likely that you’ll get an Emrakul pointed at you than a Worst Fears, so let’s go over what can and can’t be done while you’re controlling another player.
To start with, you see everything within the game they can see (so you can look at their face-down creatures, you can look at their hand, if there’s any face-down cards in exile they’re allowed to see, you can see them too). You make all the decisions they can make (you can decide to make them miss their land drop, you can make them attack into your much scarier board OR skip attacking with their evasive creature if you like, etc). You can only make legal choices- you can toss their Ultimate Price at their own mono-colored creature, but you can’t have them skip their Draw or Untap steps because that’s not a choice they have! You can also tap all their lands for no reason to make sure they don’t have mana open, but that’s less useful with Emrakul because they’ll just untap their lands as they begin the extra turn they get after this one. Finally, a change from old policy: While you can see everything THEY can see in-game, you cannot look at their Sideboard, at all. If they have a Wish-type card, like Coax From the Blind Eternities it’s legal for you to cast it, but unless there’s an Eldrazi card of theirs in Exile it won’t do anything. Even if you’re playing an older format and they have Death Wish, you don’t have the option of “blind picking” from their sideboard; you simply can’t interact with their sideboard at all while controlling them!
Finally, you can only make in-game decisions for them. You cannot make tournament decisions like having them draw or concede the game or match. You can’t force them to drop from the event, or trade you their super sweet foils, or agree to be your best friend. You might be able to convince them to share their snacks, but that has less to do with mind-controlling colorless horrors from another dimension and more to do with asking nicely, though!
Today’s Rules Tip was written by Trevor Nunez