Arcane Denial: Denial is a card that has been in and out of my list a few times. It has the one drawback of giving one opponent one extra card. However, it replaces itself, is cheap, is splashable, and it hits any type of spell. As the deck's speed increased, the counter found its way back in as additional protection and disruption especially due to the opponent having less time on average to leverage that extra card before succumbing to Azami.
Brainstorm: Brainstorm is a very potent spell. It allows me to access three new cards for the turn while having the ability to shuffle away two less relevant ones. By having several cantrips, I am able to run less lands.
Capsize: Capsize is an expensive bounce spell, however it has been very useful for me in the past. It can bounce anything and combos well with the Engine to generate infinite mana. Its mana cost is almost never detrimental.
Condescend: Condescend is a useful counterspell that also allows me to scry. It is a great counterspell in the early game and an okay counterspell late game.
Counterspell: Counterspell is a potent spell that is disruptive to the opponents’ threats and answers. It is a must include in this deck.
Cyclonic Rift: Cyclonic Rift is an amazing bounce spell. It works early while also phenomenally late game, because it can buy me a turn. The major downsides of the card is that it cannot target your own nonland permanents nor can it hit lands. It is still worth using in my opinion.
Daze: Daze is great and surprising counterspell. It has won me countless games and it is one of the free counterspells in the deck.
Delay: Delay is another cheap counterspell. It is easy to cast too. The downside of the spell only mattered about once out of fifty casts so far and even then it did not matter too much. Most of the time the game is over once the spell even comes back if it ever does.
Deprive: Deprive is another cheap counterspell. It stops mostly anything. The downside is a bummer but sometimes it is actually useful against stuff like Land Tax.
Dramatic Reversal: Reversal is another great card in this deck. Its main function is being a part of a combination with Isochron Scepter. However, Reversal is also great as a one off extra draw, for untapping Vault or Monolith, and more.
Fact or Fiction: Fact or Faction is one of the most powerful cards in Magic. It has also found a home here. It serves as a fill in for Azami in the early game as it is easier to cast. It is card advantage in the form of an instant which allows my tutors to perform more functions and making flip Jace and Snapcaster better. Fact or Fiction replaced Future Sight in this deck and I have not gone back.
Force of Will: Force of Will is a fantastic counterspell because I can cast it for free. It is tutored often and for good reason. It is one of my best answers.
High Tide: High Tide was one of the latest additions to the deck but it has been performing well. It provides another more flexible mana source in the form of an instant which makes my tutors better and more flexible. High Tide often gives me the extra three or four mana I need to win the game a turn early with a counterspell backing it up.
Into the Roil: Into the Roil is just an extra bounce spell. Cyclonic Rift and Capsize are the heavyweights in this category. However, sometimes it’s nice to just have an extra bounce spell handy and this one can cantrip. I would say I cantrip with it about thirty percent of the time.
Mana Drain: Mana Drain is one of the most powerful spells in this deck. It provides a large burst of mana in the form of an instant while also disrupting or protecting. It is insane and should be played if one can be afforded.
Mana Leak: Mana Leak is another cheap counterspell that is easy to cast. Most of the time the extra three mana tax is enough to stop the relevant spells.
Memory Lapse: Lapse is another cheap counterspell that is easy to cast. It is an excellent stall tactic especially with fewer players. Lapse is super brutal when imprinted on Isochron Scepter.
Mental Misstep: Mental Misstep is an excellent counterspell. It catches so many important cards. It is also a free counterspell for the deck. I had my doubt with the card at first. However, any doubts had dissolved rapidly. It is fantastic; run it.
Muddle the Mixture: Muddle is an okay counterspell. It costs only two mana and works most of time. However, what makes the card fantastic is that it can transmute for two cmc which is over forty percent of my spells. The fact that Muddle has both modes makes the card super awesome. I have been using it for years and love it.
Mystical Tutor: Mystical Tutor is my cheapest and most flexible tutor. It is card disadvantage but it is worth it. This card is a one mana Force of Will a lot of the times. Sometimes it gets Mana Drain. Other times it is game over by grabbing an artifact tutor.
Pongify: Pongify is in the deck to give me a way to permanently deal with creature threats. It is extremely cheap, easily tutorable, and an instant. All of those advantages allow me to remove a pesky creature efficiently before comboing off. Additionally, Pongify can serve as a combat trick to kill hatebears that way and to then discourage further aggression with my big blocker.
Remand: Remand is another great cheap counterspell. There are a lot of fancy tricks with Remand involving protecting your spells on the stack. It is an excellent tempo and defensive tool while also digging deeper into the library.
Spell Pierce: Spell Pierce is a lot like Daze. It is a very cheap and disruptive spell. It is often excellent and almost always good. It has earned its place in this deck.
Steel Sabotage: Steel Sabotage is another super cheap counterspell. It answers the most powerful cards in cEDH like Sol Ring, Mana Crypt, Mana Vault, Lion's Eye Diamond, Isochron Scepter, and so much more. Additionally, Steel Sabotage can also be used proactively. It can bounce Mana Vault and Mana Crypt for extra mana. It also is a counterspell that can be used on the combo turn to keep going off.
Swan Song: Swan Song is an excellent defensive spell. It’s main purpose is to protect Azami and the Engine. It can be used aggressively to counter ramp, tutors, Sylvan Library, and Food Chain.
Unsubstantiate: Unsubstantiate is another cheap defensive counter similar to Remand. It can protect your spells but it does not dig deeper into your library. It can also be used aggressively as a bounce spell.
Whir of Invention: Whir of Invention was an excellent addition to the deck. It can retrieve the Engine or Scepter late game. It can grab Mana Crypt early game. It can also serve as a combat trick by fetching Revoker.