Magical Hacker – Unhinged uncommon. Magical Hacker does wonderful things with planeswalkers. Clearly. But its effects on levelers aren't entirely clear. Our editors assure us that it's a hyphen (not a minus sign) between the 4 and the 6 of Lighthouse Chronologist, so there's no "Level 4+6" available. But you can still change it to "Level 7-", whatever that means.
Caldera Lake – Tempest Rare. A caldera is a crater on the top of a volcao that's caused after an eruption causes the peak to collapse. A caldera lake, then, is what happens when one of those fills with water and you get a lake on top of a mountain. So it's not just a card; it's also a fascinating geological phenomenon!
Tempest Efreet – Fourth Edition Rare. One of the primary rules of Magic is that you never put a card someone else owns into your hand. Unless you have a card Tempest Efreet, which actually changes a card's ownership in the middle of a game. Although it doesn't involve ante, Tempest Efreet is still considered an "ante card" for purposes of banning it from tournament play. You can see why.
Quarum Trench Gnomes – Legends Rare. The original printing of Quarum Trench Gnomes contains this mysterious instruction: "Use counters." Is it a recommendation for a way to remember which Plains have been targeted or a deckbuilding suggestion? You decide!
Assassin's Blade – Portal Uncommon. Officially, Portal didn't have any instants. So when it came time to add combat tricks, R&D had to invent the idea of a sorcery with specific casting restrictions. When Portal was declared Vintage-legal, these spells were mostly changed to instants, which makes a lot more sense.
Eland Umbra – Rise of the Eldrazi common. An eland is a type of antelope found in Africa. It's also (according to Wikipedia) a city in Wisconsin, an armored car, and a type of turboshaft. But the one referred to by the card Eland Umbra is the antelope.
Leviathan – Time Spiral timeshifted. Leviathan costs nine mana, of which four have to be blue. It's a 10/10 trampler with two drawbacks. It's an interesting comparison to Rise of the Eldrazi's Artisan of Kozilek.
Upwelling – Tenth Edition rare. Brian Tinsman created Upwelling for Scourge after looking through the Comprehensive Rules and realizing that rule 300.4 had never been broken before. Its wording has been changed to match up with Omnath, Locus of Mana.
Leveler – Mirrodin rare. If you zoom way in on Leveler, you can see a legend. Which one? This arcana from 2005 gives the answer!
Spawnsire of Ulamog – Rise of the Eldrazi rare. Spawnsire of Ulamog is the first card in Magic history to have an activation cost of . It's also (in a casual game) the only card that can put a theoretically unbounded number of creatures into play without any help!
Gideon Jura – Rise of the Eldrazi mythic rare. Although Gideon Jura is an accomplished mage, he prefers to wade into battle personally, using his sural (a unique bladed whip) rather than hide behind his spells.