Favorable Winds

Creatures you control with flying get +1/+1.

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.

Skycat Sovereign

Flying
Skycat Sovereign gets +1/+1 for each other creature you control with flying.
{2}{W}{U}: Create a 1/1 white Cat Bird creature token with flying.

Empyrean Eagle

Flying
Other creatures you control with flying get +1/+1.

Winged Words

This spell costs {1} less to cast if you control a creature with flying.
Draw two cards.

Squadron Hawk

Flying
When Squadron Hawk enters, you may search your library for up to three cards named Squadron Hawk, reveal them, put them into your hand, then shuffle.