Infect seems to be more popular than ever as we have been seeing it a lot, even winning major tournaments like the latest SCG Invitational. The deck is capable of winning very quickly. This might actually be the fastest deck in Modern (though that's debatable). The issue with Infect has traditionally been spot removal as you are relying on a small amount of infect creatures staying on the battlefield. The good news is that decks with a lot of spot removal like Jund and Mardu are on the decline, making Infect a better metagame choice. This is the version that made top 8 in Prague last weekend:
Many of the cards in the list we are used to seeing, but the addition of Geist of Saint Traft to the sideboard is something relatively new. Having access to Geist of Saint Traft means the deck now has a card that can win the game on its own after sideboard, and works really well against an opponent trying to beat you with all spot removal. Adding the Temple Garden to the maindeck isn't a big sacrifice. Having a plan for your more difficult matchups is very important, and it is usually necessary to devote a decent chunk of your sideboard to those plans.
Some of the slots in the deck are flexible. For instance, we have seen Spellskite in and out of the maindeck here. There were some spots where it didn't seem that impressive, but when we played against the mirror it became the best card in our deck. Some versions of Infect maindeck additional Infect creatures like Viridian Corrupter or Ichorclaw Myr, but I prefer Spellskite, as it can also protect your Infect creatures. One of the most difficult cards to beat is Walking Ballista, and Spellskite is pretty decent against it.
Losing to Tron was frustrating. I'm not confident about the hand I kept in the third game, but I do believe that the matchup is in Infect's favor. We saw the power of the deck on display since you can fight through some removal, as we saw in the case of playing against Conflagrate and Darkblast out of Dredge, and Walking Ballista from Hardened Scales. It always feels good if you are able to kill on turn three, as the games where you do have to grind through interaction tend to be much trickier.
Many of the pump spells do a similar thing so it is tough to know exactly which ones to sideboard out. Generally, protection spells like Vines of Vastwood aren't going to be as good if you are merely going for maximum damage for your mana investment. However, in the matchups you expect spot removal Vines of Vastwood and Blossoming Defense are quite important. Rancor is a card we haven't always seen in this deck, but it is important to have some ways to provide trample or evasion to get through blockers.
Infect hasn't changed much the past couple years, but that doesn't mean it isn't still a strong choice. Modern isn't necessarily about decks getting new cards, but about what the other popular decks are, and when you think about it that way it makes since that Infect is a good choice right now.
Thanks for reading,