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 this creature dies, create a 1/1 white Bird creature token with flying for each age counter on it.

Spire Owl

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

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.)

Sage Owl

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.)

Mavinda, Students' Advocate

Flying
{0}: You may cast target instant or sorcery card from your graveyard this turn. If that spell doesn't target a creature you control, it costs {8} more to cast this way. If that spell would be put into your graveyard, exile it instead. Activate only once each turn. (You still pay the spell's costs. Timing rules for the spell still apply.)

Owlbear Cub

Mama's Coming — Whenever this creature attacks a player who controls eight or more lands, look at the top eight cards of your library. You may put a creature card from among them onto the battlefield tapped and attacking that player. Put the rest on the bottom of your library in a random order.

Embrose, Dean of Shadow

{T}: Put a +1/+1 counter on another target creature, then Embrose 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

Vega, the Watcher

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

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.

Arcanist's Owl

Flying
When this creature 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.

Owlbear Shepherd

At the beginning of your end step, if creatures you control have total power 8 or greater, draw a card.

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.)

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.

Owl Familiar

Flying
When this creature enters, draw a card, then discard a card.

Augury Owl

Flying
When this creature 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.)

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.

Knowledge Is Power

Creatures you control get +X/+X, where X is the number of cards you've drawn this turn.

Owlbear

Trample
Keen Senses — When this creature enters, draw a card.

Ebony Owl Netsuke

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

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.

Derevi, Empyrial Tactician

Flying
When Derevi enters and whenever a creature you control deals combat damage to a player, you may tap or untap target permanent.
{1}{G}{W}{U}: Put Derevi onto the battlefield from the command zone.