Tyrant's Familiar

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

Skirge Familiar

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 this creature enters, 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.

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.)

Jhoira's Familiar

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

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, this creature gets +1/+1 until end of turn.

Frolicking Familiar // Blow Off Steam

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 this creature to its owner's hand.

Bramble Familiar // Fetch Quest

Judge's Familiar

Flying
Sacrifice this creature: Counter target instant or sorcery spell unless its controller pays {1}.

Geode Golem

Trample
Whenever this creature deals combat damage to a player, you may cast your commander from the command zone without paying its mana cost. (You still pay any additional costs.)

Foul Familiar

This creature can't block.
{B}, Pay 1 life: Return this creature to its owner's hand.

Lullmage's Familiar

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

Armguard Familiar

Ward {2} (Whenever this permanent 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.)

Falthis, Shadowcat Familiar

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

Thaumaturge's Familiar

Flying
When this creature enters, scry 1.

Etched Familiar

When this creature dies, each opponent loses 2 life and you gain 2 life.

Nightscape Familiar

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

Garth One-Eye

{T}: Choose a card name that hasn't been chosen from among Disenchant, Braingeyser, Terror, Shivan Dragon, Regrowth, and Black Lotus. Create a copy of the card with the chosen name. You may cast the copy. (You still pay its costs.)

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.)

Cauldron Familiar

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

Druid's Familiar

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

Necromancer's Familiar

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

Mystic Familiar

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

Palace Familiar

Flying
When this creature dies, draw a card.

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.

Pseudodragon Familiar

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

Jackal Familiar

This creature can't attack or block alone.

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.

Thornscape Familiar

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

Stonebinder's Familiar

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

Sunscape Familiar

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

Owl Familiar

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

Obstinate Familiar

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

Drake Familiar

Flying
When this creature enters, sacrifice it unless you return an enchantment to its owner's hand.

Filigree Familiar

When this creature enters, you gain 2 life.
When this creature dies, draw a card.

Thunderscape Familiar

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

Familiar's Ruse

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

Neurok Familiar

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

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.)