This is the first mission of the campaign. If you happen to be struggling with it, here is a budget, newbie-friendly deck that is designed to counter the opponent's deck.
Annihilate and
Deathstrike are your main cards to control the board and prevent the -1 health from triggering. In the instances where you are unable to prevent the -1 health, use
Horrifying Helm to stall the board, or use its spellcraft to deal lethal. If you own better cards, feel free to make improvements!
My campaign decks are all designed to be cheap and easy for new players. Check them out!