Aether Revolt was my first full on prerelease. While I had been playing the game for a long time, I had never been deep enough to start going to events like this. Mostly because I didn't know they existed until around the time Kaladesh was being spoiled.
To this day, it serves as one of my most successful and favourite prereleases. I won a door prize, I went 3-4, and I succeeded in getting one of my favourite prerelease cards since I started doing prereleases: Baral, Chief of Compliance. By that point, I wasn't much of a blue player. I played black and red a lot more frequently and even a little green periodically. However, this opened me up to typical blue control play, as well as opening me up to a brand new approach that I didn't really get into before: Izzet spell slinging. It also introduced me to cards like Goblin Electromancer and Guttersnipe.
One of the better cards that exist in Standard, currently. You're looking at a 1/3 body that you can drop very early in the game, and which allows you to play instants and sorceries for one less from their cost. Whenever you use a counter spell and it resolves you get to draw a card. While this card sees a lot more play in Commander and Modern due to how well it enables tons of great Izzet functionalities, it's also a card that enables a limited sort of effectiveness in Standard as well.
Think of it this way: all your counterspells are now cheaper. Your draw engine is entirely based around controlling your opponent, so this works flexibly in just about anything. Team this up with a Primal Amulet and Revel in Riches and make it a world easier to cast Spell Swindle and possibly win you the game. Team that up with a card like Disallow and you're laughing.
That's kind of a indirect, midrange approach, but if you'd like to be more direct Baral has you covered there too. Have a Firebrand Archer out along with Baral and a Primal Amulet and literally burn your opponent to death by controlling their play and, by proxy, enabling your draw engine as well. Through this card, your options for blue become pretty flexible and effective, especially if you're using blue for control. Baral allows you to slow down your opponent quite a bit then draw into your win condition.
Once Dominaria releases and the Kaladesh block remains Standard-legal for a short time, things are going to be kind of a wild mess. This card will see a lot more Standard play and it will likely enable quite a lot of new strategies since there's going to be Standard legal variations of cards like Lightning Bolt and Counterspell that would become enabled and much cheaper just by having Baral on the board.
This card is pretty crazy and is probably one of the best cards to see balanced play since its release in Standard. It's proof to me that Wizards still knows what they're doing when it really comes down to it, but really shows their intent when things seem kind of sloppy or weird.
True_Nephilim from TappedOut shows us a fairly popular way to play Baral in Standard: control the board, push out burn spells, and just lay the hurt constantly. It's a pretty effective and yet not an overtly overpowered way to win a game. You could easily catch someone off guard by playing some of these spells that don't see competitive play.
So what do you think of Baral, Chief of Compliance? Personally, I think it's a pretty awesome card and I hope you do too!