Welcome back! Today we’ll be covering how Brain in a Jar interacts with split cards- especially the ones with Fuse, printed in the Return to Ravnica block. Split cards are a bit different from ‘normal’ cards; instead of having just one thing, it’s basically two smaller cards printed on the same piece of card stock, usually forming a saying or pun with their name, like Fire // Ice or Life // Death. Everywhere but the stack, these cards have two sets of characteristics; Fire is a red instant with CMC of 2, and Ice is a blue instant with CMC of 2. If your opponent played a card that made you discard your blue cards, you’d discard Fire // Ice; ditto if it was something making you discard your red cards. What about casting it? Well, you announce which half you’re casting, put the card on the stack, and then completely ignore the other half. Fire // Ice is both red and blue in your hand (and your graveyard, and your library, and exile), but if you’re just casting Fire, then Fire is a red spell on the stack; the Ice half of it doesn’t exist for now, as far as the rules are concerned. Normally you can only cast one half or the other, not both, but some of the cards like Turn // Burn have “fuse”, which allows you to cast both halves if you’re casting the spell from your hand. So you could cast Turn, or Burn, or Turn and Burn together. Same as before, Turn would be a blue spell with CMC of 3 and Burn would be a red spell with CMC of 2. If fused, Turn and Burn is a red and blue spell with CMC of 5.
Now, how does that interact with Brain in a Jar? Brain’s first activated ability puts a charge counter on it, and then lets you cast an instant or sorcery from your hand without paying its mana cost, if it has CMC equal to the number of charge counters on Brain. Remember how I said Split cards have two sets of characteristics when they’re not on the stack? Here’s where that gets weird. If I activate Brain and put a second counter on it, it’ll let me cast any instant or sorcery in my hand that has CMC of 2. When it asks Turn // Burn “What’s your CMC?”, it gets back two answers: “2 and 3”. It doesn’t care about the “and 3” part; it got an answer of 2, so we can cast it. But the fun thing is, we’re not limited to just casting Burn! We can cast either half of the split card, even if the other half is much more expensive than the number of counters on our thinky-jar. You could activate it for 2, and then cast the Bust half of Boom // Bust. But even more fun- use it with those Fuse spells. Fuse lets you cast both halves if you’re casting from your hand, but it doesn’t care whether or not you’re paying. If you activated a Brain and put it to two counters with a Breaking // Entering in your hand, you could cast Breaking, or Entering, or Breaking AND Entering, for the low low cost of one mana. Not a ton of the split cards have one side so much cheaper than the other, but when you get to pull that trick it can be pretty devastating!
Today’s Rules Tip was written by Trevor Nunez (and definitely not by a Brain in a Jar)