There are a lot of decks that can fill graveyards very quickly
There are a lot of cards that already support this theme, and players love 4-color commanders because theyre rare
The deck Ive seen does run Aetherflux Reservoir like most life-gain decks should, but more often than not it is winning with combat damage thanks to Treebeard, Gracious Host
Classic and thematic artifacts return, such as Steel Overseer (a must for Modern Affinity decks), Key to the City (great for evasion and fueling the graveyard), Meteor Golem , Solemn Simulacrum , Hedron Archive and, of course, the ubiquitous Sol Ring
(11/10/2020) Untapping an attacking creature doesn't remove it from combat
Whenever this creature enters or attacks, exile up to one target card from a graveyard