Spellweaver Helix

Imprint — When Spellweaver Helix enters, you may exile two target sorcery cards from a single graveyard.
Whenever a player casts a card, if it has the same name as one of the cards exiled with Spellweaver Helix, you may copy the other. If you do, you may cast the copy without paying its mana cost.

Tanazir Quandrix

Flying, trample
When Tanazir Quandrix enters, double the number of +1/+1 counters on target creature you control.
Whenever Tanazir Quandrix attacks, you may have the base power and toughness of other creatures you control become equal to Tanazir Quandrix's power and toughness until end of turn.

Setessan Champion

Constellation — Whenever an enchantment you control enters, put a +1/+1 counter on Setessan Champion and draw a card.

Thunderclap Drake

Flying
Instant and sorcery spells you cast cost {1} less to cast.
{2}{U}, Sacrifice Thunderclap Drake: When you next cast an instant or sorcery spell this turn, copy it for each time you've cast your commander from the command zone this game. You may choose new targets for the copies.

Serra Redeemer

Flying
Whenever another creature you control with power 2 or less enters, put two +1/+1 counters on that creature.

Tribute to the World Tree

Whenever a creature you control enters, draw a card if its power is 3 or greater. Otherwise, put two +1/+1 counters on it.

Spara's Headquarters

({T}: Add {G}, {W}, or {U}.)
Spara's Headquarters enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Storvald, Frost Giant Jarl

Ward {3}
Other creatures you control have ward {3}.
Whenever Storvald enters or attacks, choose one or both —
• Target creature has base power and toughness 7/7 until end of turn.
• Target creature has base power and toughness 1/1 until end of turn.

Temmet, Vizier of Naktamun

At the beginning of combat on your turn, target creature token you control gets +1/+1 until end of turn and can't be blocked this turn.
Embalm {3}{W}{U} ({3}{W}{U}, Exile this card from your graveyard: Create a token that's a copy of it, except it's a white Zombie Human Cleric with no mana cost. Embalm only as a sorcery.)

Visions of Dominance

Put a +1/+1 counter on target creature, then double the number of +1/+1 counters on it.
Flashback {8}{G}{G}. This spell costs {X} less to cast this way, where X is the greatest mana value of a commander you own on the battlefield or in the command zone. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Eidolon of Astral Winds

Vigilance
Constellation — Whenever Eidolon of Astral Winds or another enchantment you control enters, choose target creature you control. Until end of turn, that creature has base power and toughness 4/4 and gains flying.

Cold-Eyed Selkie

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever Cold-Eyed Selkie deals combat damage to a player, you may draw that many cards.

Slime Against Humanity

Create a 0/0 green Ooze creature token with trample. Put X +1/+1 counters on it, where X is two plus the total number of cards you own in exile and in your graveyard that are Oozes or are named Slime Against Humanity.
A deck can have any number of cards named Slime Against Humanity.

Case of the Ransacked Lab

Instant and sorcery spells you cast cost {1} less to cast.
To solve — You've cast four or more instant and sorcery spells this turn. (If unsolved, solve at the beginning of your end step.)
Solved — Whenever you cast an instant or sorcery spell, draw a card.

Dusty Parlor

Whenever you cast an enchantment spell, put a number of +1/+1 counters equal to that spell's mana value on up to one target creature.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Secret Arcade

Nonland permanents you control and permanent spells you control are enchantments in addition to their other types.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Secret Arcade // Dusty Parlor

Sage of Mysteries

Constellation — Whenever an enchantment you control enters, target player mills two cards.

Eutropia the Twice-Favored

Constellation — Whenever an enchantment you control enters, put a +1/+1 counter on target creature. That creature gains flying until end of turn.

Sigarda's Summons

Creatures you control with +1/+1 counters on them have base power and toughness 4/4, have flying, and are Angels in addition to their other types.

Thickest in the Thicket

When Thickest in the Thicket enters, put X +1/+1 counters on target creature, where X is that creature's power.
At the beginning of your end step, draw two cards if you control the creature with the greatest power or tied for the greatest power.

Eidolon of Blossoms

Constellation — Whenever Eidolon of Blossoms or another enchantment you control enters, draw a card.

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.)

Porcelain Gallery

Creatures you control have base power and toughness each equal to the number of creatures you control.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Dollmaker's Shop

Whenever one or more non-Toy creatures you control attack a player, create a 1/1 white Toy artifact creature token.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)