Gigantoplasm

You may have this creature enter as a copy of any creature on the battlefield, except it has "{X}: This creature has base power and toughness X/X."

Mirror Image

You may have this creature enter as a copy of a creature you control.

Evil Twin

You may have this creature enter as a copy of any creature on the battlefield, except it has "{U}{B}, {T}: Destroy target creature with the same name as this creature."

Clever Impersonator

You may have this creature enter as a copy of any nonland permanent on the battlefield.

Protean Raider

Raid — If you attacked this turn, you may have this creature enter as a copy of any creature on the battlefield.

Mirrormade

You may have this enchantment enter as a copy of any artifact or enchantment on the battlefield.

Infinite Reflection

Enchant creature
When this Aura enters attached to a creature, each other nontoken creature you control becomes a copy of that creature.
Nontoken creatures you control enter as a copy of enchanted creature.

Dack's Duplicate

You may have this creature enter as a copy of any creature on the battlefield, except it has haste and dethrone. (Whenever it attacks the player with the most life or tied for most life, put a +1/+1 counter on it.)