Pick Magmar, maybe Starhorn or Vaath.
Pick all cards with heal.
Pick Sworn Avenger.
Pick buff cards.
Fight boss, try to draw Avenger in turn 1.
You take dmg almost each turn in small ticks, each tick will increase Avenger dmg.
Pray boss doesn't use removal.
Let Avenger do pew pew dmg to boss.
Use Sarlacs to bodyblock or increase Avenger dmg during ur own turn.
Use Bellow to stun any minion coming for your Avenger.
Win.