Empress Galina

{U}{U}, {T}: Gain control of target legendary permanent. (This effect lasts indefinitely.)

Mass Manipulation

Gain control of X target creatures and/or planeswalkers.

Invoke the Winds

Gain control of target artifact or creature. Untap it.

Emrakul, the World Anew

When you cast this spell, gain control of all creatures target player controls.
Flying, protection from spells and from permanents that were cast this turn
When Emrakul leaves the battlefield, sacrifice all creatures you control.
Madness—Pay six {C}.

Dominate

Gain control of target creature with mana value X or less.

Entrancing Melody

Gain control of target creature with mana value X.

Beguiler of Wills

{T}: Gain control of target creature with power less than or equal to the number of creatures you control.

Blue Sun's Twilight

Gain control of target creature with mana value X or less. If X is 5 or more, create a token that's a copy of that creature.

Jace, Ingenious Mind-Mage

+1: Draw a card.
+1: Untap all creatures you control.
−9: Gain control of up to three target creatures.

Agent of Treachery

When this creature enters, gain control of target permanent.
At the beginning of your end step, if you control three or more permanents you don't own, draw three cards.

Aura Thief

Flying
When this creature dies, you gain control of all enchantments. (You don't get to move Auras.)

Expropriate

Council's dilemma — Starting with you, each player votes for time or money. For each time vote, take an extra turn after this one. For each money vote, choose a permanent owned by the voter and gain control of it. Exile Expropriate.

Aethersnatch

Gain control of target spell. You may choose new targets for it. (If that spell becomes a permanent, it enters under your control.)

Commandeer

You may exile two blue cards from your hand rather than pay this spell's mana cost.
Gain control of target noncreature spell. You may choose new targets for it. (If that spell is an artifact, enchantment, or planeswalker, the permanent enters under your control.)

Charisma

Enchant creature
Whenever enchanted creature deals damage to a creature, gain control of the other creature for as long as this Aura remains on the battlefield.