Hero card

Flock Impostor

Creature - Shapeshifter

Value on arrivalDoes its thing as it enters: worth it from the first moment

Needs: Valiant

Gives: Flyers, Changeling, ETB

Not in winning lists yet: read from the card text and the graph

Build a deck with Flock Impostor as the hero

Makes it work

Mouse Trapper · Whiskervale Forerunner · Nettle Guard · Seedglaive Mentor · Veteran Guardmouse

Benefits from it

Glamer Gifter · Plumecreed Mentor · Empyrean Eagle · The Lord of the Eagles · Teo, Spirited Glider · Jackdaw Savior · Momo, Friendly Flier · Selfless Safewright

Use instead if you don't have it

Aven Interrupter · Holy Cow · Glamermite · Aang, Swift Savior · Exosuit Savior · Swarm, Being of Bees

Cards in the meta that answer it

Burst Lightning (Izzet Elemental) · Countersculpt (Azorius Control) · Get Lost (Azorius Control) · Jeskai Revelation (4-Color Control)