Here is a Mono Blue aggro decklist similar to some of the others posted in this thread.
23
Island4x
Kraken Hatchling4x
Cloudfin Raptor4x
Triton Shorestalker3x
Vapor Snag3x
Quickling3x
Military Intelligence3x
Negate3x
Nullify2x
Chasm Skulker2x
Frost Lynx4x
Pestermite2x
Bident of ThassaI feel like most of these are cards are uncontroversial.
Kraken Hatchling seems like an odd card to include in an aggro deck. But actually it has been playing very well. It is the number one most effective creature in the deck at triggering
Cloudfin Raptor. The highest base stats among our other creatures is 2/2, which means that sometimes the Raptor hits a point where it struggles to Evolve further. The Hatchling fixes this problem. It recurs well with
Quickling to buff the Raptor, attacks without fear to trigger a
Military Intelligence, and works wonders in aggro matchups. I'm not saying it is an essential card, but for this build I haven't been disappointed with it.
Chasm Skulker combos well with your draw step and the 5
Curiosity effects we are running. People might be skeptical of its slow burner nature in an aggressive deck, but our
Military Intelligence's and Bidents buff it up quickly.
Think Twice is also good with the Skulker, but
Think Twice doesn't seem a card for an aggressive list. Maybe I'm wrong, but we're really pushed for space as it is I feel.
Pestermite and
Frost Lynx provide roughly the same role. They tap down your opponent's creatures so you can get in for essential damage and card draw. I find
Pestermite better most of the time however, considering it has flying and flash.
Frost Lynx is a card I've been consistently happy with but not enough to warrant the full playset.
A playset of
Vapor Snag might be correct, but I'm juggling it with the counterspell numbers. In all the games I've played I've wanted to draw at least one counterspell. I started off running fewer
Nullify's, but I quickly found that this deck needs some form of removal and that tapping and bouncing sometimes just didn't cut it.
Negate is also very useful. It trades with removal, combat tricks, sweepers. They're both sitting at 3 copies currently. This is up for change.
Dissolve is good but I often found that leaving three mana open happened less often than leaving two mana open.
Despite 23 Islands I still get mana flooded. This shouldn't really happen but I don't feel confident dipping into 22 lands.
I have played maybe 10 games with this list so far and I have only lost one - and if that I had drawn a
Vapor Snag in that game, I would have won on the spot. I think it is really good. But it can only get better through testing. If anybody wants to try this out and suggest some improvements, I'd be honored.