Finally an English spoiler! Honestly, I expect this card to make the biggest splash in Legacy, particularly in any big mana and stompy decks with Green Sun's Zenith or Natural Order. It shuts off fetches, Force of Will, Lion's Eye Diamond, Griselbrand, Lotus Petal, Cabal Therapy, Horizon Canopy and friends (as far as mana goes), Phyrexian Mana, Dread Return, and so many others.

I honestly may be overhyped about this card, but seeing this has actually sparked my deck brewing creativity again.

Blegh. I know it's strong, but... blegh. Never liked Stop Having Fun Angel and seeing it as an extra-efficient command-viable curve-smoothing beater does not spark joy. It's probably good for legacy to shut down the little incidental payment effects, though.

*sigh* and if the angel version is anything to go by it'll tend to be an argument-causer because Final Payment and Reckless Spite are not equally stopped even if it seems like they probably should be since one is a cost and the other is loss as an effect -- or even more gratingly annoying, Mana Confluence is shut down and City of Brass is not.

And I know this is probably weird coming from me. Aren't I the Stax guy? Don't I love denial?

I am and I do. But I don't love hosers. I'm all for tax effects. I am the proud owner of a Nether Void. But I don't like Gloom. I think it's a stupid card. These sort of effects will often be worth nothing (which Wizards has "Solved" here by stapling it to a creature that sits nicely on curve and has other good effects), but when they hit they're unreasonably punishing. It's a deckbuilding roulette or, more likely, you know your friend loves their Heliod deck so you slotted in Gloom just to spite them, in particular, with extremely specific meta knowledge. This is like that: tons of decks can get by without paying life or even sacrificing things for effect but if you pull the right opponent it's a total shutdown.

I dare say there's more joy in the old color hosers. At least with Gloom and buddies you can run them with Magical Hack or Painter's Servant and feel like you actually earned the result. Here, there's no real way to cleverly manipulate the situation, it's just the good old "Were you screwed before the game began?" gamble.

EDIT: Technically, Aether Storm, and Volrath's Dungeon benefit from the effect. The latter technically can't be cheesed with Pithing Needle and can be a hard lock if the opponent has an empty hand, non-instant topdeck, and no draw power, so there's that. Credit where it's due if you pull that off.

Yeah from a standard point of view this is playable even without the final ability

As someone whose primary commander deck is Chainer, Dementia Master aristocrats, I don't particularly like this card.

Yeah my Ayara Aristocrats, as well as just my general sensibilities, makes me really hope this card doesn't pick on in my local meta. I mean it has no in built protection but it's Green/White, they can defend and recur their stuff.