Forum Familiar

Disguise {1}{W} (You may cast this card face down for {3} as a 2/2 creature with ward {2}. Turn it face up any time for its disguise cost.)
When Forum Familiar is turned face up, return another target permanent you control to its owner's hand and put a +1/+1 counter on Forum Familiar.

Pseudodragon Familiar

Flying
{2}{U}: Target creature gains flying until end of turn.

Keleth, Sunmane Familiar

Whenever a commander you control attacks, put a +1/+1 counter on it.
Partner (You can have two commanders if both have partner.)

Raven Familiar

Flying
Echo {2}{U} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When Raven Familiar enters the battlefield, look at the top three cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order.

Malakir Familiar

Flying, deathtouch
Whenever you gain life, Malakir Familiar gets +1/+1 until end of turn.

Skirge Familiar

Mystic Familiar

Flying
Threshold — As long as seven or more cards are in your graveyard, Mystic Familiar gets +1/+1 and has protection from black.

Falthis, Shadowcat Familiar

Commanders you control have menace and deathtouch.
Partner (You can have two commanders if both have partner.)

Judge's Familiar

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

Nightscape Familiar

Blue spells and red spells you cast cost {1} less to cast.
{1}{B}: Regenerate Nightscape Familiar.

Etched Familiar

When Etched Familiar dies, each opponent loses 2 life and you gain 2 life.

Stonebinder's Familiar

Whenever one or more cards are put into exile during your turn, put a +1/+1 counter on Stonebinder's Familiar. This ability triggers only once each turn.

Ertai's Familiar

Phasing (This phases in or out before you untap during each of your untap steps. While it's phased out, it's treated as though it doesn't exist.)
When Ertai's Familiar phases out or leaves the battlefield, mill three cards.
{U}: Until your next upkeep, Ertai's Familiar can't phase out.

Necromancer's Familiar

Flying
Hellbent — Necromancer's Familiar has lifelink as long as you have no cards in hand.
{B}, Discard a card: Necromancer's Familiar gains indestructible until end of turn. Tap it.

Obstinate Familiar

If you would draw a card, you may skip that draw instead.

Familiar Beeble Mascot

{TK}{TK} — Whenever this creature attacks, untap target permanent.
{TK}{TK}{TK}{TK} — Whenever a creature enters the battlefield under your control, creatures you control get +1/+1 until end of turn.
{TK}{TK} — 2/3
{TK}{TK}{TK} — 5/3

Witch's Familiar

Kediss, Emberclaw Familiar

Whenever a commander you control deals combat damage to an opponent, it deals that much damage to each other opponent.
Partner (You can have two commanders if both have partner.)

Sunscape Familiar

Defender (This creature can't attack.)
Green spells and blue spells you cast cost {1} less to cast.

Jackal Familiar

Jackal Familiar can't attack or block alone.

Jhoira's Familiar

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

Tomorrow, Azami's Familiar

If you would draw a card, look at the top three cards of your library instead. Put one of those cards into your hand and the rest on the bottom of your library in any order.

Filigree Familiar

When Filigree Familiar enters the battlefield, you gain 2 life.
When Filigree Familiar dies, draw a card.

Lullmage's Familiar

{T}: Add {G} or {U}.
Whenever you cast a kicked spell, you gain 2 life.

Drake Familiar

Flying
When Drake Familiar enters the battlefield, sacrifice it unless you return an enchantment to its owner's hand.

Owl Familiar

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

Neurok Familiar

Flying
When Neurok Familiar enters the battlefield, reveal the top card of your library. If it's an artifact card, put it into your hand. Otherwise, put it into your graveyard.

Tyrant's Familiar

Flying, haste
Lieutenant — As long as you control your commander, Tyrant's Familiar gets +2/+2 and has "Whenever Tyrant's Familiar attacks, it deals 7 damage to target creature defending player controls."

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.)

Thaumaturge's Familiar

Flying
When Thaumaturge's Familiar enters the battlefield, scry 1.

Armguard Familiar

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
Equipped creature gets +2/+1 and has ward {2}.
Reconfigure {4} ({4}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Foul Familiar

Foul Familiar can't block.
{B}, Pay 1 life: Return Foul Familiar to its owner's hand.

Biomancer's Familiar

Activated abilities of creatures you control cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.
{T}: The next time target creature adapts this turn, it adapts as though it had no +1/+1 counters on it.

Anara, Wolvid Familiar

As long as it's your turn, commanders you control have indestructible. (Effects that say "destroy" don't destroy them. A creature with indestructible can't be destroyed by damage.)
Partner (You can have two commanders if both have partner.)

Familiar's Ruse

As an additional cost to cast this spell, return a creature you control to its owner's hand.
Counter target spell.

Blow Off Steam

Blow Off Steam deals 1 damage to any target. (Then exile this card. You may cast the creature later from exile.)

Frolicking Familiar

Flying
Whenever you cast an instant or sorcery spell, Frolicking Familiar gets +1/+1 until end of turn.

Frolicking Familiar // Blow Off Steam

Cauldron Familiar

When Cauldron Familiar enters the battlefield, each opponent loses 1 life and you gain 1 life.
Sacrifice a Food: Return Cauldron Familiar from your graveyard to the battlefield.

Thunderscape Familiar

First strike
Black spells and green spells you cast cost {1} less to cast.

Thornscape Familiar

Red spells and white spells you cast cost {1} less to cast.

Druid's Familiar

Soulbond (You may pair this creature with another unpaired creature when either enters the battlefield. They remain paired for as long as you control both of them.)
As long as Druid's Familiar is paired with another creature, each of those creatures gets +2/+2.

Palace Familiar

Flying
When Palace Familiar dies, draw a card.

Stormscape Familiar

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

Fetch Quest

Mill seven cards. Then put a creature, enchantment, or land card from among the milled cards onto the battlefield.

Bramble Familiar

{T}: Add {G}.
{1}{G}, {T}, Discard a card: Return Bramble Familiar to its owner's hand.