If you've played against just about any blue cEDH deck, you know how important creatures with enter-the-battlefield triggers can be, with one key card sticking out above all else: Thassa's Oracle.
Regardless of how you feel about Thassa's Oracle in particular, we can all agree that this card essentially boils down to its one-shot triggered ability. You aren't exactly going to win the game by flickering this creature, nor is its 1/3 statline for anything worth talking about. Instead, when Thassa's Oracle comes down, its caster is making their shot: if uninterrupted, the game will come to a close.
So, how can we stop this, along with the bevy of other important creatures with enters-the-battlefield triggers currently running around cEDH? Let's take a look at another two-mana blue spell, Dress Down.
Breaking Down Dress Down
First off, the card. For , Dress Down is an enchantment with the all-important flash keyword, two triggered abilities - one which causes its controller to sacrifice it at the beginning of the end step, and another which draws its controller a card when it enters the battlefield - as well as the static ability, "Creatures lose all abilities."
Like Borne Upon a Wind, the draw trigger on Dress Down is icing on the cake, which helps to balance out the fact that this instant-speed spell unfortunately costs a non-trivial amount of mana. Two mana, only one of which being a specific color, isn't the worst thing in the world, but it sure can be rough considering the defensive nature of this spell.
Dress Down is effectively a one-turn counter for all creatures, regardless of whether or not those creatures were ever actually cast in the first place. This puts it among the likes of Force of Will and Mana Drain when deployed properly, as very few spells out there are currently capable of dealing with game-ending creatures and their triggered abilities. It may not say "counter" on it, but thanks to flash this enchantment might as well.
A Meta Call: What Dress Down Answers
We've already run through the most prolific threat, which Dress Down easily tackles, but there is a whole lot more out there which also gets hit in meaningful ways, so let's start by dissecting cEDH's strongest deck right now: Tymna and Thrasios.
A prolific infinite mana deck, TymnaThras frequently closes out games by sinking infinite mana produced by some sort of Devoted Druid combo into Thrasios, drawing the deck in the process. Two combos currently round out the Devoted Druid Druid suite: Swift Reconfiguration and Hazel's Brewmaster.
Either target an in-graveyard Devoted Druid with Hazel's Brewmaster's ETB or enchant a still-living Devoted Druid with Swift Reconfiguration to make infinite .
Now, Swift Reconfiguration isn't exactly something which Dress Down can answer - that's best left to the usual sweet of noncreature countermagic - but Hazel's Brewmaster most definitely is. Like Thassa's Oracle, we're working with a one-shot triggered ability, which, provided it targets an in-graveyard Devoted Druid as its exile candidate, will readily win the game. If you're on the other side of such a threat, then simply cast Dress Down in response to prevent Hazel's Brewmaster from ever triggering. Sure, Hazel's Brewmaster will resolve, but it'll just be a 3/4 Squirrel Warlock; not exactly the stuff of a cEDH player's nightmares.
Moving to another tournament-dominating deck, we can look to the role of Endurance in cEDH all-star Kinnan, Bonder Prodigy. There, Endurance isn't just a flexible piece of graveyard hate, but also a powerful creature which can be used as part of a layered combo in order to repeatedly draw through and shuffle its controller's library and graveyard. Pretty hard to stop with most countermagic, but not a problem with a handy-dandy copy of Dress Down in hand... and then in play.
Beyond stopping things that end games outright, Dress Down also has plenty of additional roles in preventing massive value plays and more. Is your opponent about to resolve an Atraxa, Grand Unifier? Well, sure, why not. But they absolutely don't need to resolve Atraxa's trigger. Need to hold up other interaction for later on in a turn? Then cast Dress Down in response to your opponent's Grand Abolisher: no Silence-esque effect for this turn cycle.
Where to Play It
The Master of Keys
If Dress Down is already good (and I hope that I've convinced you as much), then The Master of Keys breaks it into an all-out game-dominating staple. Provided you're able to keep your graveyard stocked (maybe you're playing Hedron Crab...), Dress Down goes from a one-shot pseudo creature counter to a repeatable one. Cast it turn after turn thanks to its escape cost (it doesn't matter that The Master of Keys will lose its abilities, that only happens once Dress Down has resolved), gaining real card advantage in the process and locking down creatures until you see a window to win.
Thrasios x Anything
I've already called out TymnaThras once before as a deck which is particularly susceptible to a well-timed Dress Down, but its grindier gameplan (and mass-mana generation capabilities) are also exactly the suite of effects which are conducive to running it with ease, as well.
Similarly, I'd argue that the strictly faster red version of Thrasios (most commonly Thrasios paired with Rograkh, though Thrasios with Bruse Tarl, Boorish Herder also lurks around some tables) can also comfortably play this card. While it isn't proactive by any means, Dress Down's ability to hit some of the most ubiquitous and otherwise minimally interactable threats is more than worth the , especially considering how much mana red-Thrasios routinely has access to.
Blue Farm
Finally, Blue Farm. While this deck may run red, Necropotence, and Ad Nauseam, make no mistake: it can comfortably play the long game, a quality which has helped it to maintain its potency in the currently slower metagame. As such, while Dress Down may be among the 101st cards for many Blue Farm players, I implore those with a more control-oriented mindset to give this card a try. It won't win games, but it will certainly save you from losing them.
Wrap Up
Dockside Extortionist may be gone, but the proof is in the decklists: a whole lot more than just Thassa's Oracle is ending cEDH games thanks to a triggered ability. Couple that with the longer, more interactive games, and why not give Dress Down a try? At the very least, you'll get to draw a card.