Ardbert, Warrior of Darkness

Whenever you cast a white spell, put a +1/+1 counter on each legendary creature you control. They gain vigilance until end of turn.
Whenever you cast a black spell, put a +1/+1 counter on each legendary creature you control. They gain menace until end of turn.

Felisa, Fang of Silverquill

Flying
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever a nontoken creature you control dies, if it had counters on it, create X tapped 2/1 white and black Inkling creature tokens with flying, where X is the number of counters it had on it.

Marchesa, Resolute Monarch

Menace, deathtouch
Whenever Marchesa attacks, remove all counters from up to one target permanent.
At the beginning of your upkeep, if you haven't been dealt combat damage since your last turn, you draw a card and you lose 1 life.

Invasion of Fiora

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When this Siege enters, choose one or both —
• Destroy all legendary creatures.
• Destroy all nonlegendary creatures.

Invasion of Fiora // Marchesa, Resolute Monarch

Jazal Goldmane

First strike (This creature deals combat damage before creatures without first strike.)
{3}{W}{W}: Attacking creatures you control get +X/+X until end of turn, where X is the number of attacking creatures.

Valkmira, Protector's Shield

If a source an opponent controls would deal damage to you or a permanent you control, prevent 1 of that damage.
Whenever you or another permanent you control becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {1}.

Reidane, God of the Worthy

Flying, vigilance
Snow lands your opponents control enter tapped.
Noncreature spells your opponents cast with mana value 4 or greater cost {2} more to cast.

Reidane, God of the Worthy // Valkmira, Protector's Shield

Sarah Jane Smith

Whenever you cast a historic spell, investigate. This ability triggers only once each turn. (Artifacts, legendaries, and Sagas are historic. To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Doctor's companion (You can have two commanders if the other is the Doctor.)

King of the Oathbreakers

Flying
Whenever King of the Oathbreakers or another Spirit you control becomes the target of a spell, it phases out. (Treat it and anything attached to it as though they don't exist until your next turn.)
Whenever King of the Oathbreakers or another Spirit you control phases in, create a tapped 1/1 white Spirit creature token with flying.

Gandalf, White Rider

Vigilance
Whenever you cast a spell, creatures you control get +1/+0 until end of turn. Scry 1.
When Gandalf dies, you may put it into its owner's library fifth from the top.

Carmen, Cruel Skymarcher

Flying
Whenever a player sacrifices a permanent, put a +1/+1 counter on Carmen and you gain 1 life.
Whenever Carmen attacks, return up to one target permanent card with mana value less than or equal to Carmen's power from your graveyard to the battlefield.

Shay Cormac

{1}: Permanents your opponents control lose hexproof, indestructible, protection, shroud, and ward until end of turn.
Whenever a creature an opponent controls becomes the target of a spell or ability you control, put a bounty counter on that creature.
Whenever a creature with a bounty counter on it dies, put two +1/+1 counters on Shay Cormac.

Sigrid, God-Favored

Flash
First strike, protection from God creatures
When Sigrid enters, exile up to one target attacking or blocking creature until Sigrid leaves the battlefield.

Tataru Taru

When Tataru Taru enters, you draw a card and target opponent may draw a card.
Scions' Secretary — Whenever an opponent draws a card, if it isn't that player's turn, create a tapped Treasure token. This ability triggers only once each turn.

Tourach, Dread Cantor

Kicker {B}{B} (You may pay an additional {B}{B} as you cast this spell.)
Protection from white
Whenever an opponent discards a card, put a +1/+1 counter on Tourach.
When Tourach enters, if it was kicked, target opponent discards two cards at random.

Teshar, Ancestor's Apostle

Flying
Whenever you cast a historic spell, return target creature card with mana value 3 or less from your graveyard to the battlefield. (Artifacts, legendaries, and Sagas are historic.)