Sending AM vs life is a very solid choice, meaning you took a big risk with a deck like this, you not understanding that and being aggressive in your answers just shows that, I only stated that you gambled on a certain matchup or a few and it didn't pay off, no need to be offended.
Sorry, I guess I tend to read comments like these as more of criticism towards a team's deckbuilding ability or ability to make good predictions during War rather than genuine curiosity regarding deckbuilding decisions. I'll work on addressing the question rather than making snarky comments in the future.
That aside, I fully understand that Antimatter causes issues for Life in general but I also feel that there are a large number of other cards that Entropy historically uses during War against Life that deserve a significant amount of consideration as well. I ultimately felt comfortable with using a deck that has no real answers versus Antimatter aside from stalling simply because I didn't predict a stall to be used versus us, I expected something similar to what we faced this round minus Pandemonium and Gravity Pull causing as many problems as they did. I don't really have any reasoning for this aside from gut feeling and having experienced what preparing for these matchups feels like for Entropy from last War. The only regret I have for this matchup is not having thought to take 34 cards in the event of facing a minimum Sideboard deck, in the event that the duel came down to deckout.
So yes, it ultimately was a gamble, but then again I feel like 95% of our deck choices are usually gambles especially during the earliest rounds of War.