If your opponent discards a card while you control Leyline of the Void, abilities that check whether a card is discarded (such as Hollow One, or a madness ability of the discarded card) still work, even though that card never reaches that player's graveyard
Jolrael, Mwonvuli Recluse Like many blue cards, Jolrael, Mwonvuli Recluse gives you incentive to draw two or more cards a turn, rewarding you with 2/2 cats
Profane Tutor One of the things I dislike the most about tutors is not having the mana to cast both the tutor spell and the one I search for, but Profane Tutor circumvents this neatly
these decks take every Hardened Scales variant they can find, and this is one of the best
While M15 seems a bit underwhelming as a whole, there are a number of cards that seem pretty sweet, either because they seem good for constructed or just plain fun
Being able to cast another five mana spell (or less mana) for free after refueling your hand can lead to some major tempo swings