mtg blue cards that return from graveyard Tameshi, Reality Architect [Kamigawa: Neon Dynasty] Each player shuffles his or her hand and graveyard into his or her library Unburial Rites - Ultimate Masters

Winning through combat damage can be difficult since players start with 40 life in Commander

I think?) also comes with a built in mana cheat

For one, this offers reusable, permanent reanimation of any creature

Rune-Scarred Demon costs a hefty 7 mana, but will let me tutor for the other half of a combo or for anything else I might need

Nearly every game involves someone's graveyard to some extent, with some decks being so dependent on recursive effects that a well-timed graveyard hoser can end their game immediately

Being a creature card instead of a sorcery opens up all sorts of recursive shenanigans (Nim Deathmantle immediately springs to mind)