Despark

Exile target permanent with mana value 4 or greater.

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

Orzhov Signet

Isshin, Two Heavens as One

If a creature attacking causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Rakdos Signet

Boros Signet

Aurelia, the Law Above

Flying, vigilance, haste
Whenever a player attacks with three or more creatures, you draw a card.
Whenever a player attacks with five or more creatures, Aurelia, the Law Above deals 3 damage to each of your opponents and you gain 3 life.

Arcane Signet

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

Agrus Kos, Spirit of Justice

Double strike, vigilance
Whenever Agrus Kos, Spirit of Justice enters or attacks, choose up to one target creature. If it's suspected, exile it. Otherwise, suspect it. (A suspected creature has menace and can't block.)

Expensive Taste

Exile the top two cards of target opponent's library face down. You may look at and play those cards for as long as they remain exiled.

Decadent Dragon

Flying, trample
Whenever Decadent Dragon attacks, create a Treasure token.

Decadent Dragon // Expensive Taste

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.)

Duelist's Heritage

Whenever one or more creatures attack, you may have target attacking creature gain double strike until end of turn.

Blood Reckoning

Whenever a creature attacks you or a planeswalker you control, that creature's controller loses 1 life.

Breena, the Demagogue

Flying
Whenever a player attacks one of your opponents, if that opponent has more life than another of your opponents, that attacking player draws a card and you put two +1/+1 counters on a creature you control.

Godless Shrine

({T}: Add {W} or {B}.)
As Godless Shrine enters, you may pay 2 life. If you don't, it enters tapped.