Karn, the Great Creator

Activated abilities of artifacts your opponents control can't be activated.
+1: Until your next turn, up to one target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value.
−2: You may reveal an artifact card you own from outside the game or choose a face-up artifact card you own in exile. Put that card into your hand.

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.)

Llanowar Elves

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Lavaspur Boots

Equipped creature gets +1/+0 and has haste and ward {1}. (Whenever it becomes the target of a spell or ability an opponent controls, counter it unless that player pays {1}.)
Equip {1}

Displaced Dinosaurs

As a historic permanent enters the battlefield under your control, it becomes a 7/7 Dinosaur creature in addition to its other types. (Artifacts, legendaries, and Sagas are historic.)

Roxanne, Starfall Savant

Whenever Roxanne, Starfall Savant enters the battlefield or attacks, create a tapped colorless artifact token named Meteorite with "When Meteorite enters the battlefield, it deals 2 damage to any target" and "{T}: Add one mana of any color."
Whenever you tap an artifact token for mana, add one mana of any type that artifact token produced.

Parallel Lives

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Hellkite Igniter

Flying, haste
{1}{R}: Hellkite Igniter gets +X/+0 until end of turn, where X is the number of artifacts you control.

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Talisman of Impulse

{T}: Add {C}.
{T}: Add {R} or {G}. Talisman of Impulse deals 1 damage to you.

Elvish Mystic

Fyndhorn Elves

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Gruul Signet

Ancient Copper Dragon

Flying
Whenever Ancient Copper Dragon deals combat damage to a player, roll a d20. You create a number of Treasure tokens equal to the result.

Birds of Paradise

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Cityscape Leveler

Trample
When you cast this spell and whenever Cityscape Leveler attacks, destroy up to one target nonland permanent. Its controller creates a tapped Powerstone token.
Unearth {8}

Seedborn Muse

Untap all permanents you control during each other player's untap step.

Sol Ring

Sneak Attack

{R}: You may put a creature card from your hand onto the battlefield. That creature gains haste. Sacrifice the creature at the beginning of the next end step.