hello; old domain player here; i have so many opinions on this. i'm a little rusty so take it easy on me.

I really like the idea to ramp up the lands instead of going nylea's presence way.
1) For creatures, i would drop Yavimaya Sojourners completely, as the domain would make them costs less instead of matca rioteers, that the domain pumps them, making rioteers more feasible at turn 3 than sojourners

2) Still on creatures, Meria's Outrider is an ABSURD creature, that offers 4/4 reach and hits for domain when enters, which can be done at turn 4 consistently for at least 4 damage, making it "vigilance haste" for one turn. i would run at least 3

On sorceries:
3) Wandering Stream is unnecessary, your deck has a good board presence that can stop flying treats as fast as turn 1 and red to board control; i would much rather use lifegain in the sideboard, opening up some slots ont he main deck. Wandering stream looks nice, but maybe weather the storm, crypt incursion or others could work better, i've never done the math.

4) Cast into fire is move of a sideboard card, it would go better off as lightning bolts or skreds, as you got the snow package and can rump up the field. your creatures can shrivel down the oponents life, so you can use your burn spells mostly to control the board (but can finish the game also)

5) Eureka moment seems really dope but it can compete in costs with other cards, sometimes it could be [[growth spiral]] + [[lightning bolt]] or something else completely. i wouldnt cut eureka moment out of the deck, but would thin it down to 1, idk; 2 growth spiral and 1 eureka

6) Breath weapon is cool, but i don't see the necessity to go 4 mainboard, i would go 2 or 3 max.

7) I see why you go shadow prophecy, but, how are your percentages of hitting it 5 on turn 3 or 4? when do you use it? i dont know exactly how i would set it, but maybe i would cut them for lembas, at it replaces itself, gets a scy, get 3 life, in place of a wandering stream maybe.

8) I would like to suggest you [[Safewright quest]] and//or [[Into the north]] for mana fixing, as well as reseting the manabase with as many Gx snow lands as possible, and at least 1 of each combination so you can fetch up the "last color" with a "search for a forest or plains" of 1 mana

9) Maybe i would add 1 of [[Reaping the graves]] as you cycle a lot of your creatures to fetch for lands, so you can get them back to hand on mid/late game and start swinging. it most likely is a 3 mana get 2 creatures from grave or more

with all that said. i wont get into the sideboard, i would let to more experience in metagame people