Casual: Combine Jace's Erasure and Whispering Madness for fast milling.

Ideally, turns 2 and 3 involve playing an unblockable creature and Jace's Erasure. Turn 4, play Whispering Madness, cipher onto unblockable creature, attack and cast Whispering Madness again. (This mills/draws the opponent for X times 4, where X is the "greatest number of cards" as described on Whispering Madness.) Turn 5, Prosperity for 4 (milling for an additional 4 with Erasure), attack and cast a cipher copy of Whispering Madness (this time for X+4). When curve allows and necessity dictates, cast defenders and Elixir of Immortality.

Note there's a lot of self-milling involved, and in casual one might play against multiple opponents (stretching the usefulness of Erasure) as well as oversized decks, thus the inclusion of Elixir of Immortality to outlast anyone. The two transmute cards, while themselves playing key roles, are also keyed into CMCs 2 and 4, which happen to be Jace's Erasure and Whispering Madness in case you'd rather go find one of those. Dimir Infiltrator is also useful in that his high toughness makes him an extra defender in a pinch.

(Conforms to Vintage restricted list)