Control Magic

Enchant creature
You control enchanted creature.

Roil Elemental

Flying
Landfall — Whenever a land you control enters, you may gain control of target creature for as long as you control this creature.

Leyline of Singularity

If this card is in your opening hand, you may begin the game with it on the battlefield.
All nonland permanents are legendary.

Empress Galina

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

Invoke the Winds

Gain control of target artifact or creature. Untap it.

Kira, Great Glass-Spinner

Flying
Creatures you control have "Whenever this creature becomes the target of a spell or ability for the first time each turn, counter that spell or ability."

Corrupted Conscience

Enchant creature
You control enchanted creature.
Enchanted creature has infect. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Perplexing Chimera

Whenever an opponent casts a spell, you may exchange control of this creature and that spell. If you do, you may choose new targets for the spell. (If the spell becomes a permanent, you control that permanent.)

Keiga, the Tide Star

Flying
When Keiga dies, gain control of target creature.

Mind Flayer

Dominate Monster — When this creature enters, gain control of target creature for as long as you control this creature.