Grand Prix Mexico City was simultaneously one of my better finishes and one of my more disappointing finishes at a Grand Prix this year. I managed to sneak into Day 2 with a very mediocre Sealed pool, 3-0 my first draft, beat Chris Fennell in the first round of my second draft, and then lose my win-and-in for Top 8 and my final match.
Here's the Sealed deck:
GP Mexico City Sealed Deck
1Ondu War Cleric
1Touch of the Void
1Lead by Example
I was very close to playing a black/green devoid deck with 1 Kozilek's Shrieker, 2 Havoc Sower, 1 Sifter of Skulls, and a Brood Butcher, but I ultimately decided that the white fliers and the support cards would be a better day 1 strategy. Unfortunately, because I lacked removal in GW, I had to splash Red for Outnumber, Boulder Salvo, and Touch of the Void, all which were great when I was able to find the red mana for them.
My deck felt pretty underpowered, but I was able to win a lot of games just by curving 2 or 3 creatures into Relief Captain and then removing their most problematic blocker with Isolation Zone or Outnumber. The white fliers (Shadow Glider, Courier Griffin) definitely over-performed, but I wouldn't count on seeing that many in drafts, since we only get 1 pack of BFZ now.
Interestingly, Seed Guardian was basically the worst card in my deck. It didn't fit with my strategy -- it's slow, it has power of only 3, so it wasn't able to attack that well, and I was never really able to get much value off of the triggered ability. Most of the time, my creatures weren't hitting the bin, and by the time they were dying, I was probably losing that game anyways. Broodhunter Wurm might have just been better, since it was only one G and has 4 power.
Gladehart Cavalry was actually in my main deck, but I sent it to the sideboard after every game 1. The card was simply too slow in my deck: I didn't really have much ramp to get it out early, so by the time I cast it, it was either win-more or I was already dead. It maybe swung the outcome of 1 match the entire day.
Unequivocally, Relief Captain was the best card in the deck. I think I won every game in which I was able to support onto 3 creatures on curve. To that end, Baloth Pup was actually a great 2-drop.
Lithomancer's Focus was also an all-star. Being able to cast a creature every turn, and then have Lithomancer's Focus to blow them out in combat or to protect a creature from, say, Searing Light or Complete Disregard, was super powerful. I think this card is the premium combat trick going forward, and should be drafted very highly for decks that are aggressive.
I don't recall all the specifics of my matches, but I was able to beat turn 3 Nissa twice, and win a game where my opponent cast Linvala and Oblivion Sower on turns 6 and 7. That said, I had at least three opponents who didn't really understand how the cards worked: two opponents in a row tried to cast Searing Light on my Baloth Pup (it looks at power, not toughness!) and another opponent who tried to sacrifice Barrage Tyrant to itself to deal lethal damage to me. When I called over a judge, who (I think?) explained that Barrage Tyrant couldn't sacrifice itself, my opponent then proceeded to try to sacrifice Barrage Tyrant to kill one of my creatures which was going to deal lethal damage to him next turn! Whoops.
I'll try to post my draft decks later. The first draft deck was great (BW Allies with 2 Steppe Glider, 1 Relief Captain, 2 Isolation Zone, 1 Oblivion Strike, Ayli, Stoneforge Masterwork), while my second draft deck was abysmal and completely built wrong. I was very lucky to beat Fennell.