Against Mono-Black Aggro, youre trying to stay alive and then turn the corner, but against Field of the Dead, you want to either kill them as swiftly as possible, shut down their engine, or win in a way that ignores their Zombies
The most popular character from Fiora is Marchesa, who aggressively politicked (including murder) her way into becoming the queen of Fiora
The other creatures that are comparable to it, have never seen widespread cube play and it needs more to be considered
Additionally, as the cards that Circu mills are exiled rather than being put in a graveyard, even decks with large amounts of recursion will suffer great losses
These utilize cards like Cloudblazer and Reflector Mage alongside cards that flicker them, like Teleportation Circle and other value engines like Panharmonicon to gradually overtake the opponent with value
Those picks are based off of my experience as a Commander player, nothing else