Mono Primal (obligatory rank 1 clickbait)

This is the deck I played to get from diamond 3 to rank 1 master this month (and marvin_the_imp played it with great success on his stream on twitch yesterday even tho he took it to throne). It started with an insane streak (19:1 to 75/100 on Dia I), but stopped working earlier today and I dropped to the bottom of Dia I. After some changes it started working again and got me to master with an 8:1 streak. The deck is a midrange deck with all the standart parts of that (removal, big units, some card draw etc.), but it has some really interesting play patterns that require a learning process.
You usually want around 3 power in your starting hand (including Etchings), but it depends on how expensive the other cards in your hand are and if you are on the play or draw (on the draw you can sometimes even keep 2 power hands). The best cards in your starting hand (if we assume that you dont have knowledge about the opponents deck) are Prism Golem, Serpent (if you can play it on turn 2) and Maveloft (if you have a good imbue target like Golem, Serpent or Jarral). If you expect control, Dazzle and market access are really good, against midrange TTS and Mave rise in value and against aggro you want From Elements.
Against aggressive decks (MonoF, Skycragg) you try to get something on the board to stick (Golem, Torgov and Linreis are the best units for that because they all survive Jekk, Mercenary Hunter). From there on you try to stabilise and go into a boardstall until you are in a favored position and can start to attack and apply pressure yourself (If your life is really low you might have to take more risks, because you want to kill the opponent before they draw burst damage. If your life total is high you can stay calm and wait until you are really ahead). Try to really think about on what to use your removal on (e.g., dont use Maveloft on a Milos on an already stabilised board if she is your only removal, because you might need her for a flyer instead). The best market choice in the early/mid game is usually Permafrost, but if you already stabilised all options are solid (Backlash might be necessary if you dont have a Dazzle and are at a low life total to have a counter to Thunder of Wings, Sear or Flash Fire.
Against midrange decks (MonoP, Xenan, FTP) you want some tempo in the early game (Serpent, Prism). At some point you usually have to decide if you are the aggressor in the game and plan your plays accordingly (If you try to win by tempo you value damage highly and try to get attacks in as often as possible. You also value the other 4 market options higher than Helio (which one you take depends on the board state). If you try to get into a value war you try to get as much value as possible out of every card. Broker for Helio or Incursion is great here. In that case you also have to think what targets to use TTS and Mave on (Mave more for immediate threats, TTS more for cards you dont want to see again at a later point)).
Against control (TJS, Worldpyre) you usually have to apply pressure, because outvaluing Grodov's Burden and Worldpyre isnt really possible for this deck (mostly because it doesnt have relic hate. I tried Formbend in the market, but its just to bad as a card to play). The important part here is to apply the right amount of pressure to force them to do things they dont want to do (e.g. playing removal instead of drawing cards/playing their value engines), but you shouldnt overcommit and play into mass removal (Equalize (fine if you have face aegis), Shen-Ra Speaks and Solar Blast) to much, except for when you have Dazzle or Backlash open. Jarral and Savage Incursion (especially with Broker) can help to close out games.
Good luck and have fun!