May Have

Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

Have

Mahadi, Emporium Master

At the beginning of your end step, create a Treasure token for each creature that died this turn. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Forge Boss

Whenever you sacrifice one or more other creatures, Forge Boss deals 2 damage to each opponent. This ability triggers only once each turn.

Bedevil

Destroy target artifact, creature, or planeswalker.

Moraug, Fury of Akoum

Each creature you control gets +1/+0 for each time it has attacked this turn.
Landfall — Whenever a land enters the battlefield under your control, if it's your main phase, there's an additional combat phase after this phase. At the beginning of that combat, untap all creatures you control.

Woe Strider

When Woe Strider enters the battlefield, create a 0/1 white Goat creature token.
Sacrifice another creature: Scry 1.
Escape—{3}{B}{B}, Exile four other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)
Woe Strider escapes with two +1/+1 counters on it.

Lagomos, Hand of Hatred

At the beginning of combat on your turn, create a 2/1 red Elemental creature token with trample and haste. Sacrifice it at the beginning of the next end step.
{T}: Search your library for a card, put it into your hand, then shuffle. Activate only if five or more creatures died this turn.

Rakdos Signet

Temple of Malice

Temple of Malice enters the battlefield tapped.
When Temple of Malice enters the battlefield, scry 1.
{T}: Add {B} or {R}.

Gratuitous Violence

If a creature you control would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Rising of the Day

Creatures you control have haste.
Legendary creatures you control get +1/+0.

Cultist of the Absolute

Commander creatures you own get +3/+3 and have flying, deathtouch, "Ward—Pay 3 life," and "At the beginning of your upkeep, sacrifice a creature."

Blood Aspirant

Whenever you sacrifice a permanent, put a +1/+1 counter on Blood Aspirant.
{1}{R}, {T}, Sacrifice a creature or enchantment: Blood Aspirant deals 1 damage to target creature. That creature can't block this turn.

Dragonskull Summit

Dragonskull Summit enters the battlefield tapped unless you control a Swamp or a Mountain.
{T}: Add {B} or {R}.

Angrath's Marauders

If a source you control would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Raucous Theater

({T}: Add {B} or {R}.)
Raucous Theater enters the battlefield tapped.
When Raucous Theater enters the battlefield, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Body Dropper

Whenever you sacrifice another creature, put a +1/+1 counter on Body Dropper.
{B}{R}, Sacrifice another creature: Body Dropper gains menace until end of turn. (It can't be blocked except by two or more creatures.)

Judith, the Scourge Diva

Other creatures you control get +1/+0.
Whenever a nontoken creature you control dies, Judith, the Scourge Diva deals 1 damage to any target.

Delina, Wild Mage

Whenever Delina, Wild Mage attacks, choose target creature you control, then roll a d20.
1—14 | Create a tapped and attacking token that's a copy of that creature, except it's not legendary and it has "At end of combat, exile this creature."
15—20 | Create one of those tokens. You may roll again.

Haunted Ridge

Haunted Ridge enters the battlefield tapped unless you control two or more other lands.
{T}: Add {B} or {R}.

Don't Have

Massacre Wurm

When Massacre Wurm enters the battlefield, creatures your opponents control get -2/-2 until end of turn.
Whenever a creature an opponent controls dies, that player loses 2 life.

Neheb, the Eternal

Afflict 3 (Whenever this creature becomes blocked, defending player loses 3 life.)
At the beginning of your postcombat main phase, add {R} for each 1 life your opponents have lost this turn.

Aggravated Assault

{3}{R}{R}: Untap all creatures you control. After this main phase, there is an additional combat phase followed by an additional main phase. Activate only as a sorcery.

Torbran, Thane of Red Fell

If a red source you control would deal damage to an opponent or a permanent an opponent controls, it deals that much damage plus 2 instead.

Combat Celebrant

If Combat Celebrant hasn't been exerted this turn, you may exert it as it attacks. When you do, untap all other creatures you control and after this phase, there is an additional combat phase. (An exerted creature won't untap during your next untap step.)

Veronica, Dissident Scribe

Menace
Whenever Veronica, Dissident Scribe attacks, you may discard a card. If you do, draw a card.
Whenever you discard one or more nonland cards for the first time each turn, create a Junk token. (It's an artifact with "{T}, Sacrifice this artifact: Exile the top card of your library. You may play that card this turn. Activate only as a sorcery.")

Mayhem Devil

Whenever a player sacrifices a permanent, Mayhem Devil deals 1 damage to any target.

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.)

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Rakdos Charm

Choose one —
• Exile target player's graveyard.
• Destroy target artifact.
• Each creature deals 1 damage to its controller.

Dolmen Gate

Prevent all combat damage that would be dealt to attacking creatures you control.

Sword of the Animist

Equipped creature gets +1/+1.
Whenever equipped creature attacks, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Equip {2}

Grim Reaper's Sprint

Morbid — This spell costs {3} less to cast if a creature died this turn.
Enchant creature
When Grim Reaper's Sprint enters the battlefield, untap each creature you control. If it's your main phase, there is an additional combat phase after this phase.
Enchanted creature gets +2/+2 and has haste.

Garna, Bloodfist of Keld

Whenever another creature you control dies, draw a card if it was attacking. Otherwise, Garna, Bloodfist of Keld deals 1 damage to each opponent.

Drivnod, Carnage Dominus

If a creature dying causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
{B/P}{B/P}, Exile three creature cards from your graveyard: Put an indestructible counter on Drivnod, Carnage Dominus. ({B/P} can be paid with either {B} or 2 life.)