Mono-Blue Mill Deck

No sideboard found.

The owner of this deck hasn't added a sideboard, they probably should...

This is a special mill deck for me because it's the first deck I put together that has specific win conditions.

Number 1: Jace's Erasure.

Ideal scenario is to have all three Erasures on the field as well as Consecrated Sphynx. Each time your opponent draws a card you can then draw 2 cards, milling them for 6 cards, effectively making them lose 7 card from their library before their main phase each turn.
Next step is to use Blue Sun's Zenith on our opponent for as many cards as possible, let's say 10, if you have the mana for it. They draw 10, you draw 20, they then mill for 60.

Number 2: Halimer Excavators.

In this deck there are four of these bad boys, and let's just say that you don't play any other allies, you'll be milling for 1+4+9+16 as they come into play. That's half of a standard deck. Put in one Umara Raptor, Sea Gate Loremaster or clone and you'll be milling for a whole deck in that turn.

If you have one Excavator on the field and can pull Rite of Replication and cast it with its Kicker cost you will mill for 36 cards.

If you have all allies on the field, played in this order:
HE, RoR(5), HE, HE, HE, Clone, UR, UR, SGL
you will mill for a total of 691 cards.

You could effectively take down 7 Commander decks or 11 standard decks.

There's a number of counter spells as well as some creature removal to protect Halimar Excavators from being killed off before the combo can be set up.
I've also adding in Evanescent Intellect to make the Allies into extra Merfolk Mesmerists in case you have spare mana before the start of your turn.