Emet-Selch, Ascian (Krrik, Son of Yawgmoth) When optimized to a cEDH level, K'rrik, Son of Yawgmoth can win as early as turn 1
Cards given out as challenge promos in the use C1 , C2 etc There are also promo cards with a D23 set ID, though the original D23 Expo set cards are part of the P1 set
These spells are always going to be good, and will likely find their way into your deck alongside or instead of the likes of Toxic Deluge and Blasphemous Act
Go for the most efficient and fastest mill as each card they lose out of their deck is great value in stopping them from being able to kill us when they land a Primeval Titan
Gwenna gains +1/+1 counters when you play creatures with power five or greater, which is great when you're ramping out cards like Bladecoil Serpent, Jodah, the Unifier, or a Rootwire Amalgam