These come in a couple of different varieties, but the big new ones are the Summons
Marneus Calgar is an engine all-in-one card, with his Chapter Master ability creating two 2/2 tokens with vigilance, giving them the ability to attack without tapping, for six generic mana, and then drawing a card off of his Master Tactician ability whenever one or more tokens enter the battlefield
These are partners that can only partner with each other
Strixhaven: School of Mages, Dungeons & Dragons: Adventures in the Forgotten Realms, and Innistrad: Midnight Hunt Commander (2021) Kamigawa: Neon Dynasty, Kamigawa: Neon Dynasty Commander, Commander Legends: Battle for Baldur's Gate, and Dominaria United (2022) When we first visited Kamigawa, there was an artifact called Kamigawa: Neon Dynasty , we learned that the artifact was improperly named as the Kappa weren't quite as dead as the denizens of Kamigawa thought
An alternate kill condition
To take for example an even wilder level up, let's go back to something from closer to the Darksteel era: Obliterate