In order to make their game more approachable to new players and to keep the game fresher, Wizards’ R&D began to emphasize creatures over spells. This has been good for the game, as now those cards that appeal to new players are actually good, and not just heartbreaking as they are easily dispatched or countered as they used to be.
The idea of a Midrange deck is that you use cards that are strong on their own, not necessarily part of an overall strategy. You find a selection of cards that have a very high quality and put them together. Its not quite that simple, but that’s pretty much it.
Today, there’s a good selection of creatures, that are both cheap and effective. Take Siege Rhino, for example. Its not the most effective creatures out there, but its very good. Its a 4/5 for four, which is pretty good, but on top of that it has two abilities, that are quite good, albeit situational. Trample is very good in a format where there’s plenty of planeswalkers, including Elspeth, Sun’s Champion, and the lifegain is important when we have very strong and fast aggro decks in the format. Even the opponent losing three life might be very good, when many decks use their lifetotals as a resource (although, with the loss of Underworld Connections this isn’t as efficient as it used to be).
The Rhino is good on its own. It doesn’t need other cards around it to be effective. You just play it and attack (or keep it back in defense). You don’t need a “Rhino Lord” to make it good.
… and there’s plenty of such creatures.
Of course, we’re not only playing creatures. Planeswalkers can often find a home in these decks. They provide constant, recurring small advantages (sometimes bigger, like Elspeth), and are usually able to be activated at least once before your opponent can get rid of them.
Those recurring advantages are quite important. Since your deck requires quite a few more lands than aggro decks, you’ll have less actual spells, and you’ll need ways to balance the situation. Some of the above cards (both creatures and planeswalkers) do much of this work for you in different ways.
The only problem is the manabase. All of these require at least two colored mana, some require three, and quite a few require mana from two or three colors. Its partly just the nature Khans of Tarkir, but its not only that. The R&D are quite willing to take the overall cost down by emphasizing colored mana over colorless. Right now that means you’ll either have to be willing to take a lot of damage or be quite slow in order to cast your spells. Either approach can be problematic, based on the situation (and what you get from being slow).
Junk (I guess Abzan now) is the combination of green, white and black. Its an excellent midrange combination of colors, since generally black is best at removing creatures, while green and white have the most efficient creatures.
Here’s an example Patrick Chapin used to win Pro Tour Journey into Nyx last spring. It was a block Pro Tour, meaning the card pool was as limited as it gets. There were plenty of midrange decks, but this color combination wasn’t very popular, most people going for BUG (or Sultai) or Naya (red, green, white) instead.
In many ways this was a pretty regular deck in the format. Since Sylvan Caryatid (the best enabler of three colored decks, best ramp, and also a good blocker) and Courser of Kruphix (a good source of steady card advantage, and a great blocker) were the most important cards in the format, most decks started with full sets of those two.
Then you have Elspeth, Sun’s Champion. Everyone knew it was the most powerful card in the format, so you’d either play with it or find a way to beat it. Chapin chose to play it. Quite a few games ended up being fights over Elspeths. The one who got his to stick would win.
Three colors (with early double color requirement in each color, see Brimaz, King of Oreskos, Sylvan Caryatid, Hero’s Downfall) require plenty of fixing and that’s why the deck plays full sets of all appropriate Temples and Mana Confluences. The Temples help smooth out draws in any way you might need, but they are quite slow.
Another long-standing color combination is Jund. Again, we have black for disruption and removal, and green for creatures, but this time red for different approach. Red also has a lot of removal, but burn spells have the added advantage of being generally able to go to the dome as well. Red also has more evasion than green or black. At least cheap evasion in the form of dragons.
Here’s an example from Simon Görtzen, which he used to win Pro Tour San Diego in 2010.
Here Putrid Leech is a strong early threat on its own, but each of the other creatures brings a form of card advantage. Broodmate Dragon, Sprouting Thrinax and Siege-Gang Commander bring more than one body to the battlefield, thus putting a great strain on any removal your opponents have, and Bloodbraid Elf cascades into another spell, probably preferably Blightning, but the card selection is such that you’ll never be in a situation where you’d accidentally cast something you don’t have targets for (as Maelstrom Pulse can target lands).
Jund is generally quite viable. There always seems to be a Jund deck out there. In the last days of the last standard, there was actually two Jund decks, one known as Jund Monsters (due to Polukranos, World Eater and Stormbreath Dragon), and the other as Jund Planeswalkers. Actually, the two decks were very similar, often just a few cards off, and there were plenty of decks that mixed the two concepts.
Jund is almost a control deck and often you’ll play like one. You try to grind the game to a halt by exchanging your resources to your opponents and then using something to get ahead. In Görtzen’s case, that something is several bodies from one creature spell, in the newer decks, its all about strong Planeswalkers and Courser of Kruphix.