Sol Ring

Arcane Signet

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

Ensnaring Bridge

Creatures with power greater than the number of cards in your hand can't attack.

Mizzix's Mastery

Exile target card that's an instant or sorcery from your graveyard. For each card exiled this way, copy it, and you may cast the copy without paying its mana cost. Exile Mizzix's Mastery.
Overload {5}{R}{R}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Kindle the Carnage

Discard a card at random. If you do, Kindle the Carnage deals damage equal to that card's mana value to each creature. You may repeat this process any number of times.

Kyren Archive

At the beginning of your upkeep, you may exile the top card of your library face down.
{5}, Discard your hand, Sacrifice Kyren Archive: Put all cards exiled with Kyren Archive into their owner's hand.

Underworld Breach

Each nonland card in your graveyard has escape. The escape cost is equal to the card's mana cost plus exile three other cards from your graveyard. (You may cast cards from your graveyard for their escape cost.)
At the beginning of the end step, sacrifice Underworld Breach.

Past in Flames

Each instant and sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost.
Flashback {4}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Ghirapur Orrery

Each player may play an additional land on each of their turns.
At the beginning of each player's upkeep, if that player has no cards in hand, that player draws three cards.

Harnfel, Horn of Bounty

Discard a card: Exile the top two cards of your library. You may play those cards this turn.

Birgi, God of Storytelling

Whenever you cast a spell, add {R}. Until end of turn, you don't lose this mana as steps and phases end.
Creatures you control can boast twice during each of your turns rather than once.

Birgi, God of Storytelling // Harnfel, Horn of Bounty

Hazoret the Fervent

Indestructible, haste
Hazoret the Fervent can't attack or block unless you have one or fewer cards in hand.
{2}{R}, Discard a card: Hazoret deals 2 damage to each opponent.

Sakashima the Impostor

You may have Sakashima the Impostor enter as a copy of any creature on the battlefield, except its name is Sakashima the Impostor, it's legendary in addition to its other types, and it has "{2}{U}{U}: Return this creature to its owner's hand at the beginning of the next end step."

Eruth, Tormented Prophet

If you would draw a card, exile the top two cards of your library instead. You may play those cards this turn.

Krark, the Thumbless

Whenever you cast an instant or sorcery spell, flip a coin. If you lose the flip, return that spell to its owner's hand. If you win the flip, copy that spell, and you may choose new targets for the copy.
Partner (You can have two commanders if both have partner.)