2019-08-23 : Archfiend of Spite’s triggered ability will trigger even if it is dealt lethal damage. For example, if Archfiend of Spite blocks a 7/7 creature, its ability will trigger when combat damage is dealt and the attacking player will sacrifice seven permanents or lose 7 life.

2019-08-23 : If the player doesn’t control enough permanents that they can sacrifice, they must lose life.

2019-08-23 : The player may always choose not to sacrifice permanents, even if they will end up losing more life than they have or if an effect (such as that of Platinum Emperion) says that they can’t lose life.

2019-08-23 : The player who loses life or permanents is the player who controls the source as Archfiend of Spite’s triggered ability resolves. In some rare cases, this may not be the same player who controlled the source as it dealt damage. If the source is no longer in the zone it was in as it dealt damage, the source’s last known information is used to determine who controlled it.

2019-08-23 : The source’s controller must either sacrifice permanents or lose life. They can’t choose to sacrifice some permanents and lose some life.