Getting all your lands back on chapter two is a nice lead into the final chapter, and honestly, summons are just really freaking cool
So, why waste the lives of your precious creatures blocking the attacker when you can simply destroy it
Terra will bin more cards long-term, but you won't know what you are milling
Instead of relying on random draws, card selection allows you to look at, choose, or rearrange the top cards of your deck
Then theres Fractured Sanity, a three-mana Blue sorcery that has each opponent mill 14 cards (discarding from their deck to their graveyard), but can also be cycled to draw a card and make opponents mill four cards instead
To close out the Khans of Tarkir block, Dragons of Tarkir saw Sarkhan Vol time traveling back to present day to find himself in an alternate timeline where the dragons never died out and the plane is ruled by clans that each worship and revere one of the five Elder Dragons