Mana Leak

Counter target spell unless its controller pays {3}.

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Journey to Nowhere

When Journey to Nowhere enters, exile target creature.
When Journey to Nowhere leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Lyev Skyknight

Flying
When Lyev Skyknight enters, detain target nonland permanent an opponent controls. (Until your next turn, that permanent can't attack or block and its activated abilities can't be activated.)

Fall from Favor

Enchant creature
When Fall from Favor enters, tap enchanted creature and you become the monarch.
Enchanted creature doesn't untap during its controller's untap step unless that player is the monarch.

Palace Jailer

When Palace Jailer enters, you become the monarch.
When Palace Jailer enters, exile target creature an opponent controls until an opponent becomes the monarch.

Serendib Efreet

Flying
At the beginning of your upkeep, Serendib Efreet deals 1 damage to you.

Thalia, Heretic Cathar

First strike
Creatures and nonbasic lands your opponents control enter tapped.

Moon-Circuit Hacker

Ninjutsu {U} ({U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Moon-Circuit Hacker deals combat damage to a player, you may draw a card. If you do, discard a card unless Moon-Circuit Hacker entered this turn.

Reflector Mage

When Reflector Mage enters, return target creature an opponent controls to its owner's hand. That creature's owner can't cast spells with the same name as that creature until your next turn.

Mist Raven

Flying
When Mist Raven enters, return target creature to its owner's hand.

Frost Lynx

When Frost Lynx enters, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.