( represents colorless mana.)
When Thought-Knot Seer enters the battlefield, target opponent reveals his or her hand. You choose a nonland card from it and exile that card.
When Thought-Knot Seer leaves the battlefield, target opponent draws a card.
Oath of the Gatewatch brought a host of powerful and efficiently costed Eldrazi creatures. One of the best was Thought-Knot Seer, it has a big body and a disrupts the opponent's hand, two factors that helped the Eldrazi tribe dominate Modern until Eye of Ugin was banned.