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.

Deadfall

Creatures with forestwalk can be blocked as though they didn't have forestwalk.

Embrose, Dean of Shadow

{T}: Put a +1/+1 counter on another target creature, then Embrose, Dean of Shadow deals 2 damage to that creature.
Whenever a creature you control with a +1/+1 counter on it dies, draw a card.

Shaile, Dean of Radiance

Flying, vigilance
{T}: Put a +1/+1 counter on each creature that entered the battlefield under your control this turn.

Shaile, Dean of Radiance // Embrose, Dean of Shadow

Sky Theater Strix

Flying
Whenever you cast a noncreature spell, Sky Theater Strix gets +1/+0 until end of turn.

Ringwarden Owl

Flying (This creature can't be blocked except by creatures with flying or reach.)
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Baleful Strix

Flying, deathtouch
When Baleful Strix enters, draw a card.

Spire Owl

Flying
When Spire Owl enters, look at the top four cards of your library, then put them back in any order.

Owlin Shieldmage

Flying
Ward—Pay 3 life. (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays 3 life.)

Jhoira's Familiar

Flying
Historic spells you cast cost {1} less to cast. (Artifacts, legendaries, and Sagas are historic.)

Jötun Owl Keeper

Cumulative upkeep {W} or {U} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
When Jötun Owl Keeper dies, create a 1/1 white Bird creature token with flying for each age counter on it.

Kangee, Aerie Keeper

Kicker {X}{2} (You may pay an additional {X}{2} as you cast this spell.)
Flying
When Kangee, Aerie Keeper enters, if it was kicked, put X feather counters on it.
Other Bird creatures get +1/+1 for each feather counter on Kangee, Aerie Keeper.

Arcanist's Owl

Flying
When Arcanist's Owl enters, look at the top four cards of your library. You may reveal an artifact or enchantment card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Aven Mimeomancer

Flying
At the beginning of your upkeep, you may put a feather counter on target creature. If you do, that creature has base power and toughness 3/1 and has flying for as long as it has a feather counter on it.

Traumatic Visions

Counter target spell.
Basic landcycling {1}{U} ({1}{U}, Discard this card: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.)

Curiosity Crafter

Flying
You have no maximum hand size.
Whenever a creature token you control deals combat damage to a player, draw a card.

Warden of Evos Isle

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

Palace Familiar

Flying
When Palace Familiar dies, draw a card.

Esior, Wardwing Familiar

Flying
Spells your opponents cast that target one or more commanders you control cost {3} more to cast.
Partner (You can have two commanders if both have partner.)

Rimefeather Owl

Flying
Rimefeather Owl's power and toughness are each equal to the number of snow permanents on the battlefield.
{1}{S}: Put an ice counter on target permanent.
Permanents with ice counters on them are snow.

Owl Familiar

Flying
When Owl Familiar enters, draw a card, then discard a card.

Sunbird's Invocation

Whenever you cast a spell from your hand, reveal the top X cards of your library, where X is that spell's mana value. You may cast a spell with mana value X or less from among cards revealed this way without paying its mana cost. Put the rest on the bottom of your library in a random order.

Ebony Owl Netsuke

At the beginning of each opponent's upkeep, if that player has seven or more cards in hand, Ebony Owl Netsuke deals 4 damage to that player.

Wing Shards

Target player sacrifices an attacking creature.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Augury Owl

Flying
When Augury Owl enters, scry 3. (Look at the top three cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Breena, the Demagogue

Flying
Whenever a player attacks one of your opponents, if that opponent has more life than another of your opponents, that attacking player draws a card and you put two +1/+1 counters on a creature you control.

Tidehollow Strix

Flying
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Parasitic Strix

Flying
When Parasitic Strix enters, if you control a black permanent, target player loses 2 life and you gain 2 life.

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Rekindling Phoenix

Flying
When Rekindling Phoenix dies, create a 0/1 red Elemental creature token with "At the beginning of your upkeep, sacrifice this creature and return target card named Rekindling Phoenix from your graveyard to the battlefield. It gains haste until end of turn."

Vega, the Watcher

Flying
Whenever you cast a spell from anywhere other than your hand, draw a card.

Aven Mindcensor

Flash
Flying
If an opponent would search a library, that player searches the top four cards of that library instead.

Judge's Familiar

Flying
Sacrifice Judge's Familiar: Counter target instant or sorcery spell unless its controller pays {1}.

Tempest Owl

Kicker {4}{U} (You may pay an additional {4}{U} as you cast this spell.)
Flying
When Tempest Owl enters, if it was kicked, tap up to three target permanents.

Stormscape Familiar

Flying
White spells and black spells you cast cost {1} less to cast.

Fable of Wolf and Owl

Whenever you cast a green spell, you may create a 2/2 green Wolf creature token.
Whenever you cast a blue spell, you may create a 1/1 blue Bird creature token with flying.

Sage Owl

Flying
When Sage Owl enters, look at the top four cards of your library, then put them back in any order.

Imbraham, Dean of Theory

Flying
{X}{U}{U}, {T}: Exile the top X cards of your library and put a study counter on each of them. Then you may put a card you own in exile with a study counter on it into your hand.

Kianne, Dean of Substance

{T}: Exile the top card of your library. If it's a land card, put it into your hand. Otherwise, put a study counter on it.
{4}{G}: Create a 0/0 green and blue Fractal creature token. Put a +1/+1 counter on it for each different mana value among nonland cards you own in exile with study counters on them.