Roil Elemental

Flying
Landfall — Whenever a land enters the battlefield under your control, you may gain control of target creature for as long as you control Roil Elemental.

Topiary Stomper

Vigilance
When Topiary Stomper enters the battlefield, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Topiary Stomper can't attack or block unless you control seven or more lands.

Kynaios and Tiro of Meletis

At the beginning of your end step, draw a card. Each player may put a land card from their hand onto the battlefield, then each opponent who didn't draws a card.

Clone

You may have Clone enter the battlefield as a copy of any creature on the battlefield.

Wood Elves

When Wood Elves enters the battlefield, search your library for a Forest card, put that card onto the battlefield, then shuffle.

Altered Ego

This spell can't be countered.
You may have Altered Ego enter the battlefield as a copy of any creature on the battlefield, except it enters with X additional +1/+1 counters on it.

Cryptoplasm

At the beginning of your upkeep, you may have Cryptoplasm become a copy of another target creature, except it has this ability.

Sakura-Tribe Elder

Sacrifice Sakura-Tribe Elder: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Eternal Witness

When Eternal Witness enters the battlefield, you may return target card from your graveyard to your hand.

Mocking Doppelganger

Flash
You may have Mocking Doppelganger enter the battlefield as a copy of a creature an opponent controls, except it has "Other creatures with the same name as this creature are goaded." (They attack each combat if able and attack a player other than you if able.)

Phyrexian Metamorph

({U/P} can be paid with either {U} or 2 life.)
You may have Phyrexian Metamorph enter the battlefield as a copy of any artifact or creature on the battlefield, except it's an artifact in addition to its other types.

Nezahal, Primal Tide

This spell can't be countered.
You have no maximum hand size.
Whenever an opponent casts a noncreature spell, draw a card.
Discard three cards: Exile Nezahal, Primal Tide. Return it to the battlefield tapped under its owner's control at the beginning of the next end step.

Progenitor Mimic

You may have Progenitor Mimic enter the battlefield as a copy of any creature on the battlefield, except it has "At the beginning of your upkeep, if this creature isn't a token, create a token that's a copy of this creature."

Noble Benefactor

When Noble Benefactor dies, each player may search their library for a card and put that card into their hand. Then each player who searched their library this way shuffles.

Undercover Operative

You may have Undercover Operative enter the battlefield as a copy of any creature on the battlefield, except it enters with a shield counter on it if you control that creature. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)

Clever Impersonator

You may have Clever Impersonator enter the battlefield as a copy of any nonland permanent on the battlefield.

Gigantoplasm

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

Body Double

You may have Body Double enter the battlefield as a copy of any creature card in a graveyard.

Vizier of Many Faces

You may have Vizier of Many Faces enter the battlefield as a copy of any creature on the battlefield, except if Vizier of Many Faces was embalmed, the token has no mana cost, it's white, and it's a Zombie in addition to its other types.
Embalm {3}{U}{U}

Jace's Archivist

{U}, {T}: Each player discards their hand, then draws cards equal to the greatest number of cards a player discarded this way.

Spark Double

You may have Spark Double enter the battlefield as a copy of a creature or planeswalker you control, except it enters with an additional +1/+1 counter on it if it's a creature, it enters with an additional loyalty counter on it if it's a planeswalker, and it isn't legendary.

Ghastly Mimicry

Enchant creature
At the beginning of your upkeep, create a token that's a copy of enchanted creature, except it's a Spirit in addition to its other types.
If Ghastly Mimicry would be put into a graveyard from anywhere, exile it instead.

Mirrorhall Mimic

You may have Mirrorhall Mimic enter the battlefield as a copy of any creature on the battlefield, except it's a Spirit in addition to its other types.
Disturb {3}{U}{U} (You may cast this card from your graveyard transformed for its disturb cost.)

Mirrorhall Mimic // Ghastly Mimicry

Heartwood Storyteller

Whenever a player casts a noncreature spell, each of that player's opponents may draw a card.

Mirror Image

You may have Mirror Image enter the battlefield as a copy of a creature you control.

Farhaven Elf

When Farhaven Elf enters the battlefield, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Stunt Double

Flash
You may have Stunt Double enter the battlefield as a copy of any creature on the battlefield.