In addition to Astarion, when Wizards of the Coast first announced the sets at Gen Con they also unveiled a card for Karlach, so it remains to be seen if she will get her own full set or if her card is simply one piece to a set shared with others.
So far assassins have only taken a single victory in my cube and that wasn't the correct way to play that particular game
With regards to Abzan, Bob has always been a strong way to break open the BGx matchup for any deck, especially in the BGx mirror
Land , Pay 1 life, Sacrifice this land: Search your library for a Mountain or Plains card, put it onto the battlefield, then shuffle
If possible, check the box since a missing trademark or a phrase about it being pre-released trading cards are signs of counterfeit cards