It has been awhile since we've had to contend with Overrun in a limited format and there are relatively few stomach punches like it. Sure, TPF has tromp but tromp can be forcast more easily by its mechanic (domainish land requirements), and thus can be anticipated more accurately. Overrun can come out of nowhere.
Yesterday I was playing an online 8-4 Xth edition draft, I had drafted a GWb deck, splashing black for removal and creature recycling. Not the greatest limited deck but one that always has a chance to win a game on the back of a pretty solid curve on the crucial 3-4-5 drop slots in X. I got matched up against a solid player with a rating in the high 1700s also plaing GW with a splash. Game one I kept a three land hand but never drew a 4th and eventually succumbed, game 2 I curved out smoothly and scored a flawless victory.
In the final game I was in control of the board thanks to a tree top bracered juggernaught and & a bracered Skyhunter patrol. Tree top bracers are a slightly under rated enchantment, granting a power boost and evasion that is superior to flying since "reach" creatures cannot block them. Don't pick them high but they can be very solid 21-22nd cards (you should almost always be playing 18 land if you are in green in XXX draft).
I also had an angelic wall in play (boarded in after seing 2x elvish riders in game 1), femerf archers, youthful knight and a pincher beetle. They were staring down the same pair of elvish riders, and a trio of elves of one type of another & a kavu climber (I think I got everything there) I'd been wearing him down and he was at 4 - I had a essence drain in hand. I was at a comfortable 14 and my opponent was at 3.
After attacking to put my opponent down to 4 I paused. Assessing the board my opponent had to either keep topdecking flyers or a wrath in order to stabalize. His only true out was Overrun. Counting up the damage I could survive an overrun if I killed one of his 3/3. On the other hand the only flyer he could topdeck the could survive my essence drain was a Serra Angel. I rolled the dice and passed the turn. My opponent type "TDFTW - I'm so lucky" and I knew he had draw Overrun.
I immediately kicked myself for not offing a rider, but tried to convince myself that I had made the right play after all the only card, in the whole set, that kills me there is overrun - nothing else in the set wins him that game in one card, what are the chances? (1/368). But in the cold light of a new day I realize that not killing the riders was a major blunder of the kind you can't make if you are planning on adding to your pack pile.
First of all: *IF* an overrun is in this card pool there is a pretty good chance my opponent has it, we were both heavy green and I didn't have it. We had both run through better than half our deck, which further increase his odds of seeing it. The most timportant point is that having realized that he had an out (however remote) I made the error of playing the odds in a win or lose proposition when I had a choice to opt out of that session of russian roulet. If I killed those riders the is no card in the set that he could have drawn to immediately win the game - the next worse card (wrath) was negated by the fact that I would be dropping a 7/7 trampling multani the next time I saw a forest. Serra angle (or disenchant effects, holyday) would merely have bought time, forcing successive top decks.
The lesson - recogize when you have a dominating board position and make sure you know the card pool. Realize that sometimes playing to win means making sure your opponent cannot win with one top deck. Especially when your opponent is playing forests in XXX and your only removal is sorcery speed.
In short the play I made maximized my chances of winning on my next turn but decreased my chances of winning over all since it kept alive his chances of winning in one card.