This lethal pairing uses Archfiend of Despair as a force multiplier for Scourge of the Skyclaves's devastating entry. When you cast Scourge of the Skyclaves with its kicker cost paid, its cast trigger immediately slashes every player's life total in half. From there, Archfiend of Despair steps in with its passive life-gain prohibition and its end-step trigger, forcing opponents to lose an additional amount of life equal to what they already lost that turn—wiping out whatever life they had left in one fell swoop.