Polymorphist's Jest

Until end of turn, each creature target player controls loses all abilities and becomes a blue Frog with base power and toughness 1/1.

Keiga, the Tide Star

Flying
When Keiga, the Tide Star dies, gain control of target creature.

Charisma

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

Oko, Thief of Crowns

+2: Create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
+1: Target artifact or creature loses all abilities and becomes a green Elk creature with base power and toughness 3/3.
−5: Exchange control of target artifact or creature you control and target creature an opponent controls with power 3 or less.

Myr Landshaper

{T}: Target land becomes an artifact in addition to its other types until end of turn.

Entrancing Melody

Gain control of target creature with mana value X.

Agent of Treachery

When Agent of Treachery 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.

Dominate

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

Mass Manipulation

Gain control of X target creatures and/or planeswalkers.

Argent Mutation

Target permanent becomes an artifact in addition to its other types until end of turn.
Draw a card.

Chamber of Manipulation

Enchant land
Enchanted land has "{T}, Discard a card: Gain control of target creature until end of turn."