Stunt Double

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

Faerie Mastermind

Flash
Flying
Whenever an opponent draws their second card each turn, you draw a card.
{3}{U}: Each player draws a card.

Deep Gnome Terramancer

Flash
Mold Earth — Whenever one or more lands enter under an opponent's control without being played, you may search your library for a Plains card, put it onto the battlefield tapped, then shuffle. Do this only once each turn.

Island

Vega, the Watcher

Flying
Whenever you cast a spell from anywhere other than your hand, draw a card.

Containment Priest

Flash
If a nontoken creature would enter and it wasn't cast, exile it instead.

Teferi, Mage of Zhalfir

Flash
Creature cards you own that aren't on the battlefield have flash.
Each opponent can cast spells only any time they could cast a sorcery.

Hushwing Gryff

Flash
Flying
Creatures entering don't cause abilities to trigger.

Watcher of the Spheres

Flying
Creature spells with flying you cast cost {1} less to cast.
Whenever another creature you control with flying enters, Watcher of the Spheres gets +1/+1 until end of turn.

Sol Ring

Ornithopter of Paradise

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Plains

Archivist of Oghma

Flash
Whenever an opponent searches their library, you gain 1 life and draw a card.

Errant and Giada

Flash
Flying
You may look at the top card of your library any time.
You may cast spells with flash or flying from the top of your library.

Tundra

Solitude

Flash
Lifelink
When Solitude enters, exile up to one other target creature. That creature's controller gains life equal to its power.
Evoke—Exile a white card from your hand.

Thunderclap Wyvern

Flash (You may cast this spell any time you could cast an instant.)
Flying
Other creatures you control with flying get +1/+1.