First, I just want to say that I did horrible tonight. But I had a lot of fun, which is all that really matters to me. I got to do some nifty stuff with Raptor Hatchling (managed to get three tokens off of one!) which has me thinking of doing something with it in Constructed, but I kind of want to see what everybody else would have built if you had had my pool.

I feel like you made the same mistake as I did initially... convinced yourself to play all 3 parts of a 3-color tribe when it would have been more consistent to cut one (in your case, white; in mine, I started tricolor pirates but cut the blue before too long).

My pool screamed pirates at me. First 6 rares I saw went redpirate, redpirate, blackpirate, boat, compass, blackpirate. I really couldn't play any other tribe when all my bombs were pirates. Unfortunately mana issues (both flavors!) and a lack of big-game removal did me in. My deck SO could have used some of them there Contract Killings.

Highlight of the day was assembling the Captivating Crew / Makeshift Munitions combo and living the dream. I'll steal your Air Elemental, attack you with it, then throw it at you!

Actually, red and white were the best colors in the first deck. Green cards had a bad habit of sitting in my hand, and if it wasn't green cards sitting in hand it was Forests showing up when I needed Mountains. The Prying Blade was not as useful as I hoped it would be in facilitating three-color play. Although if I had run Commune with Dinosaurs I might not have had that problem.

Before the last round started, I reexamined my Merfolk because three of the people who beat me were running a lot of Merfolk (though one never touched blue) so I thought I'd just build one and see how it ran for the last round. And then I got the bye, cause there was an odd number of people at the event. So I just unsleeved everything, put my cards away, and went around watching some of the other games.

My pool was:







Blue was an obvious keep.
I felt that my low cost white wasn't impactful enough, and red had a bunch of aggro 3-4 drops while providing nearly no 2 drops, so these were out.
Tried UB for a match since UG felt weak to flyers and somewhat suffering of having bad hard removal, but I found myself too much on the backfoot due to a high curve and lowish stats. (lost agains GR dinos).
Switched to UG to benefit from a better curve and the deck performed surprisingly well: 3 wins in the loser bracket, with a draw between the second and third one due to my opponent going away after I lost the first game thanks to his RB deck with 13 pirates, atreasure map and that banner that pumped his pirates and let him draw an extra card each time he casted one,plus 2 of the pirate raise dead and removal just to be sure.
Cheap stuff+instant speed interaction meant that I was able to keep the pressure up when I curved out, and decently sized bodies+ draw and tempest caller with cancel back-up in the deck made for a decent plan b. Always managed to race the varous flyers.

Was tempted to run the quartermaster with two cuirasses, but I feared it was too cloggy and with only one the fail case of having both looked a lot worse that the best case to me.
Shore keepers was to have more early drops, it never blocked and got cracked in multiple games. Didn't feel I wanted one with the wind due to a lack of removal magnets, but it might have been a mistake, keeping mana up for cancel was pretty easy in merforks.
Deeproot waters just looked bad, so I didn't test it. Jace was ok, not really exciting obviously, but still decent, found myself dropping it and plussing more than I expected, but in one case it might have been a mistake.

I don't have the list for my pool, sadly, but I had a very solid one. Legion's Landing, Conqueror's Galleon, Hiuatli, and 5 or so removal spells. Went undefeated.

The transform cards did a lot of work when I got them online, and the boat was easy to turn on. Only got to play the PW once. Format seems like one of the better sealed formats.