Maximizing this Sultai commander requires combining creatures with lots of keyword abilities (Nightveil Predator, Venomthrope) with cards that sacrifice them (Phyrexian Altar, Deadly Dispute) to stack a bunch of keywords on Rayami
Then you gain 3 life if that player has more life than each other player
Consequently, players interested strictly in winning will most likely have no better option than mono-red aggro as we move into the next Standard season
The good news for the aftermath cards is that flashback is an extremely powerful mechanic, since it not only generates card advantage but also allows for some tricks to generate value only from the graveyard (a good example of this is Gnaw to the Bone in Dredge, which doesn't really plan on drawing and casting the card from its hand but instead just attempts to mill it into the graveyard and cast it with flashback)
With over 27,000 different cards printed (and counting) printed over the history of Magic: The Gathering , anyone who claims to know exactly how all of them work is probably not telling the whole truth