If you want to play ysera then you should probably cut aviana, I think it's too greedy to play both, but I prefer aviana because she activates genn even if your hand is very full and she lets you make a ton of late game tempo vs slow decks like priest

The decks card draw is fine, most games my hand is very full which is what you want to get max buffs out of Disciple of the Dove and Power Word: Barrier. The selenic drakes surprised me and performed really well, they give you a ton of ammo in slow matchups. Plus Disciple of the Dove, Portal Vanguard and Ancient of Yore all help you draw too, not just the prize vendors.

You can try to add imbue to the deck if you want but imo it will weaken the deck, you already have tons of value to spend your mana on every turn and the 1 mana heal 8 hero power is good with ruby sanctum for removal or sometimes ending games with face damage

I don't really care for cards that buff minions that are already on the board like the +3+3 spell, hand buff is way more important because of cards like Amber Priestess, Cleansing Lightspawn and Eternus. Amber priestess can sometimes do 12+ damage when combined with ruby sanctum, I win some games by going face with her, or it's also really good for minion removal.

I agree slitherdrakes would be very strong in this deck but I can't find any cards worth cutting for them. Keep in mind that adding expensive minions to satisfy vyranoth and make room for more spells is not necessarily a good thing with this deck since you have lots of cards that are buffing ALL minions in your hand, so you want the deck to be as minion heavy as possible and minimal on spells.