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.

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.

Rewind

Counter target spell. Untap up to four lands.

Pacifism

Enchant creature
Enchanted creature can't attack or block.

Plains

Aven Gagglemaster

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

Riddleform

Whenever you cast a noncreature spell, you may have Riddleform become a 3/3 Sphinx creature with flying in addition to its other types until end of turn.
{2}{U}: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Stormwing Entity

This spell costs {2}{U} less to cast if you've cast an instant or sorcery spell this turn.
Flying
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
When Stormwing Entity enters, scry 2.

Concordia Pegasus

Griffin Aerie

At the beginning of your end step, if you gained 3 or more life this turn, create a 2/2 white Griffin creature token with flying.

Island

Swift Response

Cancel

Mistral Singer

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

Roaming Ghostlight

Flying
When Roaming Ghostlight enters, return up to one target non-Spirit creature to its owner's hand.

Revitalize

Waker of Waves

Creatures your opponents control get -1/-0.
{1}{U}, Discard Waker of Waves: Look at the top two cards of your library. Put one of them into your hand and the other into your graveyard.

Frantic Inventory

Draw a card, then draw cards equal to the number of cards named Frantic Inventory in your graveyard.