Commence the Endgame > Sublime Epiphany: Commence the Endgame is not very good, even at low power. For an instant-speed six-drop, Epiphany offers much more utility.
Dreadhorde Invasion > Skyclave Shade: Dreadhorde invasion was no Bitterblossom. Skyclave Shade inserted in the spot to bolster aggro.
Falkenrath Noble > Gravebreaker Lamia: Aristocrats has several options at lower CMCs than Noble. Flipping it for Lamia, which is intended to bolster the Bx graveyard strategies.
Eternal Taskmaster > Nightmare Shepherd: A test swap, as our black section gets a little higher on the CMC curve. Nightmare Shepard was a beast in the arena cube.
Hammer of Purphoros > Rekindling Phoenix: Hammer, while a fan favorite among my friends, never preformed. Swapped for Rekindling Phoenix, which is just so difficult to kill off.
Decimator of the Provinces > Kazandu Mammoth: Decimator never saw play - literally. Mammoth lowers the curve a little bit but will definitely see more main-deck play.