EDIT: I took out 1 monk and 1 zealot to allow for 2 crystal flowers. the flowers are essential in dealing with some threats you will face on ladder. These were the only 2 cards I could remove 1 of, without hurting the deck. I will let you guys know of any other changes when they happen.
This is my own optimal version of Y rush. I dropped the Khalim's training as it's maybe slightly clunky. You don't really need it too often, and there are other cards I'd prefer way more.
Air Elemental for one. This card enables the fastest start times in the game, you can be on the opponents God faster than a Face Hugger on bath salts.
I feel the inclusion of Monk is also great as it gives you some more draw beyond prayer. I prefer this guy over khalim's Follower.
Sagittarius is a great card, but 3 maybe a little much. The fact this guy is a Faeria engine is the main reason to play him. He can chip away at slower decks faces though as well and gen faeria simultaneously which is great. You might wanna put the 3rd in your deck if you are having problems drawing them, but I always seemed to end up with 3 of them in my hand, which is pretty useless really... so 2 it is.
I take 3 crusaders because they are so strong in this deck. You could get away with 2, but having 3 means you can play more loose with them and use one earlier to trade if need be.
And don't forget because this is a face deck, you are supposed to trade as well. if you can run in a Wind Soldier to clear something, do it. With soul drain this can clear most threats. Of course wind soldier is great to hit face and power up crusader, too. Just don't be afraid of trading these guys in though if you need to.
Demonic salmon is probably my favourite card in the deck, it can snowball out of control and win you games alone if played correctly. You can use it as a bait creature as well by playing it and going face with enemy creatures near by, knowing they will use attacks on killing this. Ideally you want to use shaytan demons as bait though and maybe your ele's as well if you can as the if the salmon is able to go unchecked it can get you ready to drop a crusader and win the game.
Shaytan demons should be played early, they can win you a game in a few turns if unchecked. when in tandem with the other threats they are extremely deadly, and normally will be answered if at all possible. this also makes them perfect candidates for bait. Just be mindful that each one of these guys takes 2 health off you each turn, so be careful playing them late game. Also if you are loosing too much health and you can't trade them away, don't hesitate to soul drain your own guy to save your health and heal a little bit back.
Shay tan demons are the backbone of the deck, and drawing into 2 of these guys early when combines with the likes of demonic salmon, monk and wind soldier can be deadly, and win you games in a couple of turns.
Flash salmon is mainly just for powering up crusader, that's why I don't personally have 2 of them. They aren't that good for trading into stuff like the wind soldier, so really they are only there for buffing crusaders. They are good however at sniping queens assassins, shaytan assassins and lionfish, things with low health and deathtouch basically.
Closing notes regarding monkey. Monkey is an amazing early play, getting these dudes down can help you swing tempo in your direction. They rely on you leaving the wells alone though, and for the most part this is what you want to do in rush. However, If you get a turn one elemental, walking that guy up the map to trade him in is a slog, and he gets in the way of your saggy as well, so what I tend to do with them is put them into double collection if there is nothing else for the guy to do. Games tend to not go on that long so it doesn't matter all that much, but that extra 4 to 6 faeria can win you a game.
My point is that if you play monkey with this guy sitting on a well you are going to loose value. You have to either move your elemental out of double collection the turn before playing your monkey (if being played later game) or just hang onto them IMo as it's not worth not getting the full buff on it for 1 faeria. This is why I think some people will have issue of having both monkey and the elemental with saggy in the deck too. You need to get that ele out of the line of site of your saggy, and the natural thing for it to do is double collect.
You can just use the ele for trading as it has 4 damage, but it won't survive with it's low health so it would essentially be a suicide mission.
I don't know, I do think the Ele is best used as a double collector if the game can allow for it, so monkey might be taken out of the deck for another haste creature. It is just great at being sticky if you play it when you're supposed to though.
So I think that covers it really, the rest is self explanatory and it's not like this is a new archetype.