Before anyone says anything, I am aware of the fact that discard as a mechanic never really faded away completely.
Much like some of the more basic mechanics that have through the history of Magic, discard has always kind of been a thing. It's primarily used to gain card advantage by preventing your opponent from holding on to key cards. However, one of the main problems that discard keeps running into is the attempt to balance its cards by limited what you can and can't choose to discard from your opponent's hand - if you even get to see their hand at all. There have been cards like Inquisition of Kozilek and Thoughtseize that blew that wide open, but we haven't seen anything like that in Standard rotation in a long time. Plus, the closer we get to them, the worse discard is for the rotation in general.
While you're not going to see anything like The Rack or Bloodchief Ascension anytime soon, discard is still incredibly close to being very effective. With the release of Nicol Bolas, the Ravager and the remainder of the Core 2019 set, it's become apparent to anyone that appreciates the strategy that it's currently the most effective it's been in years. Even better, while you currently have some versatility in how you build your discard deck, a good deal of the staples will be the same.
Today I'd like to go over some pieces you'll want to build a discard deck in Standard.
Nicol Bolas, the Ravager should be an automatic include in nearly every deck, especially one that's focused around discarding your opponents' cards. You'll almost never flip him in Standard, but he works as a brilliant equalizer if you manage to.
What you have here is an extremely efficient flyer that forces opponents to discard upon ETB. Not only that, he also gives a good reason to splash non-black colours, and comes in swinging high as a 4/4. Given he's a lot more useful in a format like Modern or Commander, that doesn't mean he's no good in Standard. This guy is just straight value no matter how you slice it and, in my opinion, probably the best Bolas card Wizards has printed. Believe me, they've been trying.
If you're going to play discard to any kind of effectiveness beyond card advantage, you'll want to run one of these, if not both. As an enchantment, Raiders' Wake is way more effective and harder to remove. Plus it rewards a more aggressive strategy with its Raid mechanic, forcing a discard if you attacked with a creature.
While Fell Specter is less effective to this end, you still get an immediate two damage just for having this creature resolve. If you play both, you drop people down four damage for each card discarded.
What makes any good deck, especially in Standard, is a cohesive finisher that decisively ends a match. While Torment of Hailfire requires more setup, it's also far more effective in closing out a match. You want to put an opponent in a position where they don't have the option to discard or sacrifice a permanent, forcing them to bolt themselves for each mana you put into the X cost.
Fraying Omnipotence may require less setup, but it's also a lot less dependable. The only way it becomes as effective is if you have an opponent with cards in hand while you have permanents that drain life for discards. However, it could give you enough of an advantage to quickly tie off a match.
Your endgame and ramp-into creatures will change depending on what kind of approach you want to take. Out of these three, each has a balance keeping them from being auto-includes.
Herald of Anguish is a beast: it's a 5/5 with flying that forces your opponents to discard upon your end step. However, that's balanced out by the insane cost, and the fact that it requires a good arsenal of artifacts in order to be considered truly effective. You could run a set of Implement of Malice, or something to make that workable, but that just takes away from the fact that you're making a discard deck.
Urgoros, the Empty One is less effective as a creature and needs to connect to force the discard, but has the additional bonus of giving a bonus to you if they go to discard. Meanwhile, Dreamstealer works as a pretty effective way to empty an opponent's hand, has pretty decent evasion and recursion that makes him way more effective. However, in the end he just costs way too much to recur.
While this isn't an automatic include in a discard focused deck, it certainly is a value-packed card if you choose to run it. With Angrath, the Flame-Chained you have an effective synergy in his first ability that forces an opponent to discard a card and lose two life. This works in tandem with the other static effects I've mentioned earlier. Then there's his third ability, which works as an extremely effective finisher, even if it'll almost never go off.
Another card that's not an automatic include. Cabal Stronghold still works as excellent ramp in the mid-to-late game should you be running mostly Swamps which, honestly, if you're running an effective discard deck, you should have anyways.
Last but not least, Liliana's Spoils isn't an auto-include, or even really necessary. But, if you're looking for reasons to filter out the top of your deck and you don't want to slot in a blue card strictly for that purpose (something like Strategic Planning, for example) this might be a good option for you.
Of course, you're also going to want to run a suite of removal, counters, and draw spells, but that really depends on your play style and the direction you plan on taking your deck.
I would highly recommend you slot in enough removal or bounce spells to make Torment of Hailfire the ultimate closer. Counters aren't exactly necessary. I might slot in a few in the sideboard just to stick it to a few deck types, such as U/W Gift or U/W Approach. What you do with the rest is up to you! I hope you enjoy!