Its a strong addition for at least Cube and casual EDH, and at least Standard sideboard play
2015-11-04 The cost reduction can apply to alternative costs such as flashback costs
2 Emet-Selch, Unsundered/Hades, Sorcerer Of Eld From FFXIV Fill Your Graveyard, Then Use It As Your Second Hand Though Emet-Selch won't completely eradicate the board like a Rejoining eradicates a world, he can be dangerous if allowed to go unchecked for long enough
Pir, Imaginative Rascal // Toothy, Imaginary Friend Together, Pir and Toothy can lead a fun Counter deck, likely +1/+1 Counter with various other Counter themes
Mystic Sanctuary: great fetchable utility land, can set us up with an extra turn with Walk the Aeons or even infinite turns with Venser, Shaper Savant in conjunction with the afromentioned extra turn spell
In a game already dense with variance, coin-flip cards can make matches even more chaotic