Steel-Plume Marshal

Flying
Whenever Steel-Plume Marshal attacks, other attacking creatures you control with flying get +2/+2 until end of turn.

Gale Swooper

Flying
When Gale Swooper enters, target creature gains flying until end of turn.

Thriving Heath enters tapped. As it enters, choose a color other than white.
{T}: Add {W} or one mana of the chosen color.

Whenever Falconer Adept attacks, create a 1/1 white Bird creature token with flying that's tapped and attacking.

Up to two target creatures each get +2/+2 until end of turn.

{1}{W}, {T}: Tap target creature. Activate only if you control a creature with flying.

Target creature gets +2/+2 and gains lifelink until end of turn. (Damage dealt by the creature also causes its controller to gain that much life.)

Destroy target tapped creature. You gain 1 life for each creature you control with flying.

Flying
When Aven Gagglemaster enters, you gain 2 life for each creature you control with flying.

Defender (This creature can't attack.)
Attacking creatures you control get +1/+0.