Thought experiment: if Expropriate was a modal spell and the first one was Ponder for UU, would it be broken?
It's already broken enough, so...yeah
However, I think it wouldn't be treated the same as Finale of Devastation. I believe most players psychologically don't see playing a non-ultimate'd Finale as a downer. Whereas, if Expropriate had that lesser mode, few players would ever play it for the lesser mode, even if it was the right play.
Ponder is a bigger step down from Expropriate than Green Sun's Zenith is from ultimate-form Finale. Having a creature Wargate'd into play is still more than good.
I think a better card to reference it against would be Cyclonic Rift. Rarely played for it's 2 cmc mode, but still clutch when you have to. Except Cyclonic Rift is a powerful answer card (perhaps the best), and it cannot be a finisher on its own. Finale is an okay answer card (sorcery speed), and can still be a devastating finisher on its own.
By the way, I play and resolve Ad Nauseam a bunch. I play it a bunch because my main deck has 60 lands. I get to resolve it because I'm playing it in a pod where I'm trying to win with Maze's End. I wouldn't say it's a problem card in cEDH or non-cEDH.
It's already broken enough, so...yeah
However, I think it wouldn't be treated the same as Finale of Devastation. I believe most players psychologically don't see playing a non-ultimate'd Finale as a downer. Whereas, if Expropriate had that lesser mode, few players would ever play it for the lesser mode, even if it was the right play.
Ponder is a bigger step down from Expropriate than Green Sun's Zenith is from ultimate-form Finale. Having a creature Wargate'd into play is still more than good.
I think a better card to reference it against would be Cyclonic Rift. Rarely played for it's 2 cmc mode, but still clutch when you have to. Except Cyclonic Rift is a powerful answer card (perhaps the best), and it cannot be a finisher on its own. Finale is an okay answer card (sorcery speed), and can still be a devastating finisher on its own.
By the way, I play and resolve Ad Nauseam a bunch. I play it a bunch because my main deck has 60 lands. I get to resolve it because I'm playing it in a pod where I'm trying to win with Maze's End. I wouldn't say it's a problem card in cEDH or non-cEDH.