Doric, Owlbear Avenger

Vigilance, trample
When this creature transforms into Doric, Owlbear Avenger, other legendary creatures you control get +2/+2 and gain trample until end of turn.
At the beginning of your upkeep, transform Doric.

Doric, Nature's Warden

Vigilance
When Doric, Nature's Warden enters, search your library for a Forest card, put it onto the battlefield tapped, then shuffle.
Whenever Doric attacks, you may pay {1}{G}. If you do, transform her.

Doric, Nature's Warden // Doric, Owlbear Avenger

Elminster

Whenever you scry, the next instant or sorcery spell you cast this turn costs {X} less to cast, where X is the number of cards looked at while scrying this way.
+2: Draw a card, then scry 2.
−3: Exile the top card of your library. Create a number of 1/1 blue Faerie Dragon creature tokens with flying equal to that card's mana value.
Elminster can be your commander.

Edgin, Larcenous Lutenist

Each nonland card in your hand without foretell has foretell. Its foretell cost is equal to its mana cost reduced by {2}. (During your turn, you may pay {2} and exile it from your hand face down. Cast it on a later turn for its foretell cost.)
Whenever you cast your second spell each turn, goad target creature an opponent controls.

Karlach, Fury of Avernus

Whenever you attack, if it's the first combat phase of the turn, untap all attacking creatures. They gain first strike until end of turn. After this phase, there is an additional combat phase.
Choose a Background (You can have a Background as a second commander.)

Minsc & Boo, Timeless Heroes

When Minsc & Boo, Timeless Heroes enters and at the beginning of your upkeep, you may create Boo, a legendary 1/1 red Hamster creature token with trample and haste.
+1: Put three +1/+1 counters on up to one target creature with trample or haste.
−2: Sacrifice a creature. When you do, Minsc & Boo, Timeless Heroes deals X damage to any target, where X is that creature's power. If the sacrificed creature was a Hamster, draw X cards.
Minsc & Boo, Timeless Heroes can be your commander.

Jaheira, Friend of the Forest

Tokens you control have "{T}: Add {G}."
Choose a Background (You can have a Background as a second commander.)

Lae'zel, Vlaakith's Champion

If you would put one or more counters on a creature or planeswalker you control or on yourself, put that many plus one of each of those kinds of counters on that permanent or player instead.
Choose a Background (You can have a Background as a second commander.)

Holga, Relentless Rager

Haste
Holga, Relentless Rager must be blocked if able.
Whenever Holga attacks, each creature you control attacking a player gets +1/+0 until end of turn for each creature that player controls.

Halsin, Emerald Archdruid

{1}: Until end of turn, target token you control becomes a green Bear creature with base power and toughness 4/4 in addition to its other colors and types.
Choose a Background (You can have a Background as a second commander.)

Astarion, the Decadent

Deathtouch, lifelink
At the beginning of your end step, choose one —
• Feed — Target opponent loses life equal to the amount of life they lost this turn.
• Friends — You gain life equal to the amount of life you gained this turn.

Volo, Itinerant Scholar

When Volo enters, create Volo's Journal, a legendary colorless artifact token with hexproof and "Whenever you cast a creature spell, note one of its creature types that hasn't been noted for this artifact."
{2}, {T}: Draw a card for each creature type noted for target permanent you control named Volo's Journal.
Choose a Background

Minthara, Merciless Soul

Minthara has ward {X}, where X is the number of experience counters you have.
At the beginning of your end step, if a permanent you controlled left the battlefield this turn, you get an experience counter.
Creatures you control get +1/+0 for each experience counter you have.

Volo, Guide to Monsters

Whenever you cast a creature spell that doesn't share a creature type with a creature you control or a creature card in your graveyard, copy that spell. (A copy of a creature spell becomes a token.)

Simon, Wild Magic Sorcerer

Whenever you cast an instant or sorcery spell with mana value 3 or greater, roll a d20.
1-9 | Each player draws a card.
10-19 | You draw a card.
20 | Copy that spell. You may choose new targets for the copy.

Shadowheart, Dark Justiciar

{1}{B}, {T}, Sacrifice another creature: Draw X cards, where X is that creature's power.
Choose a Background (You can have a Background as a second commander.)

Wyll, Blade of Frontiers

If you would roll one or more dice, instead roll that many dice plus one and ignore the lowest roll.
Whenever you roll one or more dice, put a +1/+1 counter on Wyll, Blade of Frontiers.
Choose a Background (You can have a Background as a second commander.)

Minsc, Beloved Ranger

When Minsc, Beloved Ranger enters, create Boo, a legendary 1/1 red Hamster creature token with trample and haste.
{X}: Until end of turn, target creature you control has base power and toughness X/X and becomes a Giant in addition to its other types. Activate only as a sorcery.

Gale, Waterdeep Prodigy

Whenever you cast an instant or sorcery spell from your hand, you may cast up to one target card of the other type from your graveyard. If a spell cast from your graveyard this way would be put into your graveyard, exile it instead.
Choose a Background (You can have a Background as a second commander.)

Themberchaud

Trample
When Themberchaud enters, he deals X damage to each other creature without flying and each player, where X is the number of Mountains you control.
You may exert Themberchaud as he attacks. When you do, he gains flying until end of turn. (An exerted creature won't untap during your next untap step.)

Xenk, Paladin Unbroken

Double strike
Auras you control have exalted. (Whenever a creature you control attacks alone, it gets +1/+1 until end of turn for each instance of exalted among permanents you control.)