Tide Skimmer

Flying
Whenever you attack with two or more creatures with flying, draw a card.

Island

Essence Scatter

Lofty Denial

Counter target spell unless its controller pays {1}. If you control a creature with flying, counter that spell unless its controller pays {4} instead.

Castle Vantress

Castle Vantress enters tapped unless you control an Island.
{T}: Add {U}.
{2}{U}{U}, {T}: Scry 2.

Soul of the Rapids

Flying
Hexproof (This creature can't be the target of spells or abilities your opponents control.)

Cloudkin Seer

Flying
When Cloudkin Seer enters, draw a card.

Spectral Sailor

Flash (You may cast this spell any time you could cast an instant.)
Flying
{3}{U}: Draw a card.

Gust of Wind

This spell costs {2} less to cast if you control a creature with flying.
Return target nonland permanent you don't control to its owner's hand.
Draw a card.

Warden of Evos Isle

Flying
Creature spells with flying you cast cost {1} less to cast.

Winged Words

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

Sage's Row Denizen

Whenever another blue creature you control enters, target player mills two cards.

Witness of Tomorrows

Dungeon Geists

Flying
When Dungeon Geists enters, tap target creature an opponent controls. That creature doesn't untap during its controller's untap step for as long as you control Dungeon Geists.

Mistral Singer

Flying
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)