Please Note: I do not play PvP, nor do I spend money on packs, thus I do not have all the cards that could benefit this deck further.
This deck, unlike my others, requires a little bit of setup, but the payoff will outpace the AI fairly quickly with all the lifesteal.
Xenan Lifespeaker on Turn 1 is pretty much a must for it, but if not, you don't have to worry too much about it. After Lifespeaker is out, you'll definitely want to get
Cult Aspirant or
Disciplined Amanera onto the field. Then the fun really starts to pick up once
Katra, the Devoted gets played. Your creatures will start getting so many +1/+1s that the AI will have no response to them.
If you find yourself lacking you could always enjoy
Xenan Fanatic, especially after giving them lifesteal.