Draw/Mill/Beat down/WIN (2021 STD) (Standard)

4 win conditions.
1) Play Peer into the Abyss (targeting your opponent), causing them to draw half their library. Then using Folio of Fancies to get them to mill the rest, emptying their library, for a "no draw" win.
2) Play Peer into the Abyss (targeting your opponent), causing them to draw more cards than they have health, and then have Underworld Dreams finish them off.
3) Play Peer into the Abyss (targeting yourself) and then have Teferi's Tutelage mill your opponent for twice (or four) times the amount of cards you drew, emptying their library, for a "no draw" win.
4) Use Folio of Fancies, in combination with Underworld Dreams or Teferi's Tutelage, to either drain your opponents health or library as needed.

Maddening Cacaphony - Awesome card for a mill deck. Loads up Drown in the Loch in the early game and can be retrieved lated for massive removal.
Peer into the Abyss - Allows for most of the win conditions by either enabling a "mill" win or a "damage" win. Can also be used to draw massive amounts of cards, almost certainly giving you what you need for a win.
Duress - To be used in conjunction with Stern Dismissal or Unsubstantiate to remove non-creature threats like enchantments, artifacts, spells or plainswalkers.
Unsubstantiate - Used to send various threats back to your opponents hand. Pseudo-counters all non-creature spells, like plainswalkers, enchantments and even other counter spells. Can be used to remove an attacking creature from combat and remove any/all auras attached to it.
Stern Dismissal - This is one of the few blue/black cards that can remove an enchantment from the field once it has been successfully played, making it almost essential. It can also remove an attacking creature from combat and remove any/all auras attached to it.
Erebos's Intervention - A "save the day" card. It can be used to recover a huge chunk of life and remove a problem at the same time.
Drown in the Loch - An awesome card in this deck (once it is properly prepared). Countering or killing any card that has a lesser CMC than the number of cards in your opponents graveyard is extremely useful.
Confounding Conundrum - The 'shut fetch land down' card. If two or three are on the field, your opponent will return two or three lands to their hand.
Underworld Dreams - Deters your opponent from using too many draw triggers. Also can end the game quickly when paired with Peer into the Abyss. Can be used with Folio of Fancies to remove large chunks of your opponents health each turn.
Teferi's Tutelage - Fills up your opponents graveyard, which increases Drown in the Loch and So Tiny's effectiveness. Can win the game by causing a "no draw" situation when used with Peer into the Abyss or Folio of Fancies.
So Tiny - This is a very flexible card because it can stymie early rushes or make late game thumpers useless. Especially useful against vampire decks. They don't gain life with life link or do damage with deathtouch.
Mystic Subdual - Again, a really useful card in mid to late games because that turn 4 beast that has flying, trample, this, that and activates every triggered ability under the sun is now just a law ornament. Makes god card normal by removing the "not a creature" ability. Mutate has no effect. Tapping to do something is not an option anymore. All you have to do is deal with any damage the creature may do by attacking.
Frogify - Has the same functionality as Mystic Subdual but lessens the potential attack damage a creature can do.
Folio of Fancies - Very useful, flexible card that allows for half the win conditions. Also draws a few cards at the end of your opponents turn if needed.
Tormod's Crypt - Because I'm that guy. All those cards I milled, goodbye!
Mystic Sanctuary - Puts Maddening Cacaphony back into your hand for another mill. Puts Erebos's Intervention back into your hand for more health gain. Very useful card in this deck.
Clearwater Pathway - Mana stability.

A short run down of game play would be:
Enchant early creatures as they make it onto the field, prioritizing which kind of enchantment to use if able, So Tiny for damage triggering threats, Frogify for large ability creatures, Mystic Subdual for smaller ability creatures. Instants for mid game threats, either bouncing and removing with Stern Dismissal/Unsubstantiate and Duress or Drown in the Loch for flat out removal. While at the same time setting up your win conditions. Drawing an extra card happens as needed and when acceptable to do so. Finally, on turn 7 (fastest) you play Peer into the Abyss, targeting your opponent, getting them to draw half their deck and lose half their health and then be finished off by 20+ Underworld Dreams triggers.