Lay your fears aside, and let Jund terrorize you no longer! Beating Jund is far from impossible.
People clamor that Jund is the only "viable" deck in today's Standard, but this is simply untrue. It may be the "best" deck available, but I think this depends highly on the metagame. People are still playing decks that lose to Jund. And then they complain about Jund's prevalence. Perhaps it annoys players that you actually have to try to beat Jund in order to beat it. The deck choice matters, and the gameplay decisions matter. The sideboard definitely matters.
At the local level, I have noticed that Jund decks tend to take over the top spots at tournaments by climbing over the following kinds of decks: other Jund decks (especially those built or piloted badly), Vampires, slower or less consistent red-based decks (like Boros), Allies, suboptimal green midrange, or random combo.
A lot of these deck strategies aren't designed to beat Jund explicitly – they were designed by asking questions like the following: which Vampires/Allies are the best? What are the strongest creatures in xyz colors? How do I get off a particular combo? These are fine ways to design decks sometimes, but often, in competitive arenas, the first and foremost question you should be asking is: How do I beat the best decks? Whether it be Faeries, Jund, or Thopter Depths – if you want to stand up to the metagame, well, they don't call them "decks to beat" for nothing.
So if you're ready to venture into Standard and plan on beating Jund, here are the ways you could go about it.
1. Overwhelming Board Presence
Try to get as many creatures as you can on the board using as few resources as possible. Usually this involves token-producers like Emeria Angel, Bestial Menace, Master of the Wild Hunt, etc. Another way is to use Planeswalkers like Elspeth or Nissa Revane.
2. Unanswerable Threats
Jund dislikes creatures it can't handle. Kor Firewalker and White Knight in combination makes a white weenie deck pretty much unstoppable against Jund. Although you are sacrificing some power against decks of the wrong colors. One possible solution is to leave the Firewalkers in the sideboard and maindeck just the White Knights. It helps to make your bears a little more threatening somehow – potentially through equipment enhancements or with Elspeth backup or other creature pump. There are larger threats that Jund can't handle, like Thornling and Sphinx of Jwar Isle. Incorporating these into your deck, assuming you can reach that amount of mana reliably, will win games by themselves. It's important, also, that assimilating these unanswerable threats takes as few resources as possible.
There are lots of cards that seem like they'd fit this category but somehow aren't good enough. The regenerating creatures in Standard, for instance. They're too undersized/unevasive to pose a real threat to Jund, and the fact you need mana open to keep them around is an issue. There's one creature that seems borderline, and that is Uril, the Miststalker. Jund can't deal with it using any of its removal spells. However, its lack of evasion actually makes it too slow despite its seemingly decent size. Despite not having an explicit answer, Jund DOES have answers to ground creatures, and that is lots of chump blockers from Sprouting Thrinax or Siege-Gang Commander.
3. Overwhelming Card Advantage
Jund's long-term goal is to "out-card advantage" you. But it has limited ways of doing this – Blightning, tokens, and Cascade. If you can "outrace" their card advantage, you will be ahead. Arguably, any deck that wants to beat Jund reliably must have this condition met. One could lump #1 in the list here, too, if one wanted to – tokens are kind of like card advantage. Cards like Mind Spring, Ranger of Eos, and Mind Sludge all offer ways of one-upping Jund's card advantage.
What about sweepers like Day of Judgment? Normally sweepers can provide card advantage, but against Jund it's not as effective. Sprouting Thrinax leaves 3 power behind after a Wrath. And Jund can quickly replenish with Bloodbraid or Siege-Gang. The best methods of gaining card advantage against Jund are to: A) put more threats down with fewer cards, B) draw more cards, C) make Jund discard cards. It is harder to try to remove Jund's creatures.
4. Using the Philosophy of Fire
Of course, probably the most reliable way of beating Jund is to play a mono-red (or mostly red) burn deck like the one that won GP Kuala Lumpur recently. The deck takes advantage of Jund's nonexistent answer to burn – Jund has no life gain and no way to prevent it. Of course, there are creatures in the deck, too, but Jund has very few answers to them since the Unearth ability gets around spot removal nicely and most of the creatures need instant-speed answers. This deck is Jund's worst nightmare.
Many people have figured out these ways of beating Jund, but people still aren't beating it. Why is that?
I feel the primary reason is that people forget that, when fighting Jund, they are not fighting just one deck. They're fighting two. Pre-board Jund and post-board Jund are two different monsters. It is essential to test against both in order to see how good your matchup is against Jund. And even then, Jund sideboards are VERY flexible. They can run cards that you may not even know existed in Type 2.
Fortunately for you, Jund players are trending towards a certain kind of build – namely Simon Gortzen's deck from Pro Tour San Diego. They may not copy his exact list, but they use a lot of the same elements, particularly from the sideboard. Study it well, and try testing your deck against his pre- and post-board version. If the matchup doesn't "feel" all that different, try sideboarding more cards. Consider very hard whether cards like Blightning or Sprouting Thrinax should leave. They are often quoted as being "Jund's best cards", but there are definitely times to take them out.
The only cards I keep for sure are Bloodbraid Elf and the lands. I've sided all the other cards out at some point, depending on the matchup, and depending on what I had to replace them with. Lightning Bolts also tend to stay more often than not. But yes, I've sided out: Blightnings, Thrinax, Rampant Growths, Leeches, Broodmate Dragons, Siege-Gangs, and removal spells. This is how flexible Jund is when it sideboards – it's a morphing machine. So even though, as you look through the Top 8 list, you see "just a bunch of Jund decks" with the same old cards. The sideboard is really half the deck. The decks you see aren't the decks you will play against. Each deck, each sideboard represents a slightly different matchup for you. And depending on how the opponent will sideboard and what cards he or she has, the matchup can be good for you, excellent for you, or even terrible for you.
But, as I mentioned, a lot of the decks are conforming these days. So try using Gortzen's build as your ruler.
Then, try to build a Jund deck that "crushes" your deck, given the right sideboard cards. Now adjust your own sideboard in an attempt to counterbalance such a deck.
For instance, if your deck tries to create an overwhelming board presence, and your Jund opponent has Chain Reactions or Jund Charms in the sideboard. How do you combat that? Pro-red creatures? Not overextending? Negates or Brave the Elements?
If your deck has "unanswerable" threats, and your Jund opponent has some combination of Vampire Nighthawks, or Basilisk Collar, or Fleshbag Marauder. Does your deck still hold up?
If you're playing a lot of white cards, how do you deal with Malakir Bloodwitch? Mind Control? Non-white fatties?
If your deck has lots of card advantage spells, how does it handle Duress and Mind Rots?
If you are playing mono-red, well, Jund doesn't have much of a sideboard against mono red. You might want to test against 4 Bolts, 4 Terminate, and X Bit Blasts. And maybe an added Mind Rot. A lot of Jund decks seem to have given up this matchup, though, so mono-red is in good position here!
Some may say it is excessive to test against a sideboarded Jund deck specifically built to beat a particular m atchup, but I think it is a good way to get an idea of how bad the matchup can really be. Because Jund players are a dime a dozen, and they all know what decks they have to beat to win. They are specially tuning their sideboards just for the people that want to beat them, like yourself! So you have to be ready for the worst.
Good luck and good hunting!