I am not sure about the cards in the side:
Ashiok can be a game changer vs control deck, it can remove from the game powerful resources from the opponents deck and vs creature it can create new threat, walls, etc.
However, it can be summoned only on the third turn, and it will be hard to protect him for at least one turn.
I am actually considering to add in the side a
duress to play against control deck, in that way, i'll be able to remove
counterspell/draw engine from my opponents hand, but i am not sure yet which card i should remove.