Cast ramp cards and mana dorks in the early game, cast big dinosaurs in the late game.
Why Gishath?
Dinosaurs's come in 3 colours, Gishath's a 3 colour dinosaur, and it easier to cast than Zacama (especially the second or third time). Plus, I already owned a Gishath.
Why Dinosuars?
Casting and attacking with big creatures is fun? Also the core of the deck is from Ixalan block so if Brawl continues to be a thing it should survive rotation in good shape. Also, I seem to have lots of good dinosaurs in my draft remains.
Deck Colours
Because of the lands and fixing available in standard legal cards, it's best to stick to two colours with (maybe) a splash. Dinosaurs work here because we're primary in green and run so much ramp. Looking around at other Gishath deck lists and I have no idea how people splitting their 1 and 2 drops evenly across 3 colours make it through the early game consistently.
Green The primary colour since green has all the ramp.
Red The secondary colour since red/green has the best two colour dinosaur in Regisaur Alpha, and red has the best tutor/combo piece for dinosaurs in Forerunner of the Empire.
White White is almost a spash for Zetalpa, Primal Dawn. White also gives us access to good removal in Cast Out and Ixalan's Binding. While white does have some good small creatures, we avoid them to focus on casting our ramp cards on curve.
Strategy
Opening Hand. Keep the five land hands. Don't keep a 2 land hand unless your ramp and fixing is really good.
Early Game. Cast your ramp, mana dorks, and cost reduction cards so the big dinos can be cast on curve or early.
Mid Game. Try and hold off casting Gishath, Sun's Avatar until later in the game when your hand is nearly empty. Preferably when the blue player is tapped out. Preferably when you can hit someone for damage and get free dinosaurs into play.
Key Cards
Polyraptor combo's with Forerunner of the Empire to create 7 tokens Polyraptors (Forerunner's ability is a may ability). Combo's with Shake the Foundations.
Mirage Mirror This card is insane! It's probably good in any Brawl deck. It copies anything, not just creatures, not just your cards. Make it a copy of your oppoenent's Angel of Sanctions and then use their ability to exile it!
This dino deck is 3 colours, which makes mana a little tricky with the list of Standard cards, so the deck is primarily 2 colours: green and red. Green has the best ramp cards, so green is clearly one of the choices. The best gold dinos are red and green, plus Optec Hunmaster and Forerunner of the Empire. Looking at the decks on EDHRec, I don't see how they can run little creatures in all 3 colours without problems.
Notable Exclusions
Carnage Tyrant, Zacama, Primal Calamity, Heroic Intervention are out due to budget constraints. Not enough chance to play Brawl to make these worthwhile.
Kinjalli's Caller, Kinjalli's Sunwing and other low CMC white cards are out because the fixing is so bad using standard legal cards.
Card Categories
Card Draw
Card draw is almost completely reliant on the Amonkhet cycling mechanic. Five lands have cycling plus Cast Out, and Beneath the Sands. The only other card draw is from Ripjaw Raptor. Ripjaw Raptor's card draw is fragile since he's on a creature and requires damage to trigger enrage.
Recursion
Currently only running Atzocan Seer. Will add Wildest Dreams, which is an awesome card but what to cut?
Ramp
Atzocan Seer, Beneath the Sands, Channeler Initiate, Cultivator's Caravan, Drover of the Mighty, Druid of the Cowl Harvest Season, Knight of the Stampede,
optec huntmaster
, Thunderherd Migration
Tutors
Commune with Dinosaurs, Forerunner of the Empire, Gishath, Sun's Avatar, Growing Rites of Itlimoc
Targetted Removal
Abrade, Cast Out, Ixalan's Binding, Savage Stomp, Burning Sun's Avatar
Weaknesses
The deck relies primarily on creatures and combat damage so it's vulnerable to combo's and board wipes. The big dinosaurs are not exactly subtle, and landing a big one, especially early, draws a lot of attention and marks you as a target. Heroic Intervention would probably be a help here but it's a little pricey for a card that's rotating soon. Gishath, Sun's Avatar is pretty important in the late game and he's expensive to cast (and re-cast!). He's a magnet for removal so you usually only get one hit/activation before he's sent back to the command zone.
Card Draw. Late in the game you're in top deck mode without a good way to get card advantage and rely on cycling. Cycling is awesome late game, but looking ahead to September 2018 we're going to lose all our cycling cards and will need something else. At that point Vanquisher's Banner will probably be a must-have rather than a maybe.
Recursion. Losing a key threat sucks. Atzocan Seer is currently the only way to get things back. Will add Wildest Dreams, but what to cut?
Possible Cuts and Additions
Growing Rites of Itlimoc
is a great card, but seems to be low impact and surprising hard to flip. I tend to only have 1-3 dinos on the battlefield late game. Stays in for now, maybe replace it later.
Ixalan's Binding. Probably replace it with Wildest Dreams or Settle the Wreckage.
Burning Sun's Avatar. Another good card that I'm thinking of removing for Etali, Primal Storm, which looks like a multiplayer bomb.
Links
https://www.channelfireball.com/articles/getting-stuck-into-magics-newest-format-3-lists-for-brawl/