Put out your Diligent Excavators and Altars of the Brood, before dropping a ton of 0-CMC artifacts, returning them all to your hand with Retract (or, even better, Paradoxical Outcome), and doing it all over again! The Diligent Excavator also mills upon you casting either of the legendaries in the deck too: Jhoira, Weatherlight Captain and Erayo, Soratami Ascendant.
So yeah - the Erayo in the room...he's just there for some lols. Just make sure you drop it as the second (not third) spell in a turn - if an opponent tries to remove it via creature removal/creature damage as a response to you casting your own third spell, it will count the opponent's removal spell as the fourth spell and flip before it gets removed. If you cast it as the first spell, it's open to removal the whole way through casting the 3 other spells, and if it's the third spell, an opponent may be able to respond to the flip trigger itself with creature removal/creature damage, meaning the removal/damage goes through before it's flipped. The amount of opponents - at least on MTGO - that just don't realise how it works, and waste important spells as the first spell on their next turn, is astounding! Sometimes they even epic fail twice and do it again the next turn, not realising what even just happened!
Day's Undoing may seem anti-combo to the deck, but you can either use it in the early game after dumping 0-CMC artifacts to the board to be able to Retract later, or - to totally screw up opponents - you can cast it, and then activate a Tormod's Crypt while it is on the stack, which means you exile their graveyard before Day's Undoing resolves, meaning your opponent doesn't even get to shuffle it into their deck!
The deck is surprisingly good against graveyard tactics (such as Delve/Grizelbreanimation decks), compared to other mill decks, because of Days/Crypt - that's 6 cards that stop your opponent's cards being in their graveyard! I've often had opponents using decks like this concede after I wipe their graveyard in this way.
It is also great against another normal Storm deck, since you can use a Quicken and a Grapeshot to steal their own Storm Count from under them and cast it as a response to their own Grapeshot! A Quicken is also in the main deck to allow you to Day's Undoing on an opponent's end step, meaning you get a fresh hand without even ending your own turn!
If the opponent's deck is actually good against Mill, then you just swap out all the mill elements and start playing with Reckless Fireweaver and Grapeshot. This is basically two decks in one! (I personally tend to sideboard in the Fireweavers/Grapeshot automatically in the second game, regardless, simply to throw my opponents off, since because it's an unknown, non-meta deck, they assume mill is all its got and sideboard badly against the burn they don't know is coming their way!)
But even if your opponent does have a plan against the Storm side of the deck, and has a Damping Sphere handy, you've still got Abrade and Void Snare to get rid of it entirely, as well as two Chief Engineers in the sideboard (to allow you to get around the Sphere's added costs somewhat, until you draw the necessary removal before you combo off properly).
Yes, the land count is extremely low, but a ton of your deck costs nothing and there's so much draw going on that you're bound to hit the few lands you need soon enough. You've also got some Paradise Mantles in there to be able to equip to a creature to turn them into a mana rock, at a push: I have rarely had mana problems with this set-up, and if I do, even 1 land lets you at least get out an Altar of the Brood, and an Artificer's Assistant to be able to scry nonlands to the bottom while starting the mill engine going. The one and only issue that can occur, land-wise, is drawing only Mountains in your opening hand in the first game - if this is the case, absolutely mulligan!
