1) Why does this Infect list run U/G? While Mono Green Infect tends to have a smoother curve, with the banning of Invigorate the Mono Green version of Infect has lost the quickness and effectiveness it once had. Because it can no longer race faster than any of the aggressive decks in the format, it means Infect either has to be resilient or run a greedier game plan to keep up. By running blue we have access to Slip Through Space and Blighted Agent to slip past enemy blockers, as well as a stronger sideboard plan with cards like Dispel and Aura Flux. The deck also has access to Simic Growth Chamber as a dual land, allowing us to bounce lands to guarantee value off of cards like Groundswell.

2) How fast does the deck kill? Well, without interaction Pauper Infect can kill as soon as Turn 2 with a god hand of Turn 1 Glistener Elf into Turn 2 double Groundswell with a Mutagenic Growth. The more accurate answer to this question is likely around Turn 3-6, especially since most of our creatures come down on Turn 2 and since most Pauper decks run interaction we likely need to spend some time to be able to protect our threats as well.

3) Why run Infect over any other Aggro deck? This question varies off of your personal playstyle, as Infect is a deck that can punish idle opponents more than Stompy or Affinity can at the cost of resiliency. This Infect list can win by Turn 4 on average with no interaction by the opponent, and an opponent's Gainlands will do nothing for them. And again, sideboard options in Infect are often better than Stompy's.