Proving this point, Murders at Karlov Manor proved that its possible to balance serialized releases
Cauldron Familiar Aside from being my favorite black card ever printed, Cauldron Familiar is an insane creature that has wrecked many formats, including Eternal ones such as Modern, thanks to its nasty tendency of being oppressive enough to shut down aggro decks, or even to go infinite with cards such as Samwise Gamgee and any sacrifice outlet
Sephiroth fits beautifully there, helping to smooth out the curve in a deck that often lacked a solid three-drop outside of Grist
While you cant directly give someone gems from outside Arena, codes for the different items in the games store do exist
Each creature your opponents control dying from a boardwipe will shoot 1 damage per creature, with every creature dying creating its own Gimli trigger
Get enough Persistent Petitioners in play, or make a ton of copies of them, and youll quickly be milling your opponents out of the game