This deck is built around twin superstars Enigma Drake and Drake Haven. Drake Haven turns this deck into a source of endless Drakes, enough to overwhelm most opponents. The problem is that this plan can be too slow, especially on the draw. If you spend your third turn on investment, then the fourth turn on a few Drakes, is that going to be good enough to turn the corner? I had a number of test games where it was not. You will need all the mana efficient ways you can find to impact the board while the engine gets going.
That is why this build maximizes the mana efficiency of your actions while setting up Drake Haven, as well as the speed at which you can get Enigma Drake to full strength. You want to always be discarding spells rather than creatures, so as much as I would love the option, even Curator of Mysteries is not good enough. Better to stick to the base plan and maximize its effectiveness. Getting Bedlam Reveler online quickly is often as important as a powerful Enigma Drake, especially when you need leftover mana for Drake Haven activations. If your opponent is causing you long-term unsolvable problems on the ground, or Drake Haven does not have time to turn the corner, you want Enigma Drake to kill in 2 or 3 hits.
You absolutely need Lightning Axe and Shock to give yourself a tempo game, and a way out of what would otherwise be hopeless board states. I do not want to cheat on the numbers here. When those cards are bad, you will often be able to discard them, and you can sideboard them out for counters in the appropriate matchups. I tried counters in the main, but they clashed constantly with the rest of what I set out to do. Note that Shock is here mostly because of the need to kill Saheeli Rai. If that stops being a concern, you likely prefer at least 2 copies of Magma Spray. Having access to 5 or 6 such spells would be very reasonable.
Fiery Temper is a free bonus whenever you find it, but it may come as a surprise that this deck does not attempt to use any other madness cards, or anything that works out of the graveyard. The reason for this is that other such cards are not mana efficient, and mana efficiency is a far bigger concern than getting maximum value out of your cards. There are games where you exhaust your deck and run out of action, especially if you hit a land pocket in the midgame, but not enough of them to merit making sacrifices to try to salvage those games, which would be difficult in any case.
While I did not especially want to play Anticipate, you need additional ways to dig for your key cards and to smooth out your mana. Playing Cathartic Reunion on turn 2 often forces you to risk either mana flood or screw, so you both would prefer to wait in order to learn what you want to discard, and Anticipate is a way to get you out of that trap if things go badly.
The land situation is tricky since the cycling lands are only for Allied color pairs. You still want some since flooding is a serious problem, but this deck cannot afford tapped lands on crucial turns. You also don’t want to use cycling lands as an excuse to play more lands, because that weakens Enigma Drake and Bedlam Reveler in addition to the extra mana cost. Often you will need all your mana on every turn, sometimes even including turn one. I’m not certain whether 4 such lands is correct—my confidence interval is from 2 to 6. 20 lands is a small number given how much you do not want to not miss your fourth and even fifth land drops, but you often draw a large number of extra cards and flooding after a bunch of cycling can be quite bad. I added Anticipate to the deck largely because I felt I could not afford to add more lands.
The sideboard is speculative, as the deck mostly does not want to change. Some decks won’t have targets for your red removal, in which case you can bring in a counter package, and when you want board sweepers they are available and don’t kill Enigma Drake or Bedlam Reveler. Niblis of Frost seems like a logical option in some matchups, but I do not have a particular enemy in mind for it.