Most of the self mill cards in green hit your library for just four and only select for one card type
Decks that rely on fast mana, like combo decks, can go as low as 14 lands, as they make use of mana rocks like Lotus Petal or cards like Dark Ritual to add mana and cast as many spells as they can to execute their combo
Grand Crescendo Token decks need ways to protect themselves from board wipes
Only creatures you control at the time Song of Totentanz resolves, including the Rat tokens it creates, will gain haste
See rule 702.84, Unearth. 702.84a: Unearth is an activated ability that functions while the card with unearth is in a graveyard
Casting Cost: Card Type: Legendary Creature - Mutant Mercenary Hero Power / Toughness: 5 / 3 Card Text: As Deadpool enters, you may exchange his text box and another creature's