I also put a second Olivia, Mobilized for War in the sideboard, for opponents who aren't playing Lightning Bolt, but it's possible that we'd rather have a Kalitas, Traitor of Ghet instead, for the decks that do
Legality depends on the tournament format -- Cloud, Planet's Champion can be legal in some formats and banned or restricted in others
Threats are outpacing reactive cards significantly in terms of power level, which makes it difficult for decks like this to survive
The idea is to play Archfiend and then play Metamorphic Alteration on an opponent's creature to turn it into an Archfiend of the Dross
Starting with the player whose turn it is, each player in turn order chooses up to two creatures they control, then all of the creatures not chosen by any player are sacrificed at the same time